On the 180 or 160 question, my first decision made at upgrade time from P45+ to 160 was simply due to cost. The 180 was considerably more expensive and I just did not have the budget to cover the 180 upgrade and tech camera.
Since then I have been lucky enough to work with a 180 2x and now a have briefly have a 280 (my back is in for repair for the wifi cover). What I found out was that the files in 16 bit when worked up from the 180 quickly get to 2GB in size and can approach 3GB with layers. I am not a Mac user, but have a pretty fast Windows machine and have been working with the Wx systems since around 1986. I don't personally feel a mac (new or current) will process the files any faster. A 3GB file takes time to save, layering gets cumbersome and I tend to shift on everything I shoot even if I don't want a pano since I like to shift. Never know if I will want one later. Add in the LCC for each image and things just get pretty big. I noticed right away with a 384MB raw conversion from the 180. Wonderful images, I can't take a thing away from them. Just big.
The one feature I miss on the 180 is the sensor plus at 20MB instead of 15MB on the 160. There are many times I just can't shoot at 50 due to outdoor conditions and for now the 260 at iso 400 is pretty much the same as the 160. Just a bit too much noise and loss of color details. Tech cameras can exacerbate this more since many of the lenses I shoot need a CF and this will cut down exposure by 2.5 stops on average. I have read all the posts on just how well you can uprez the sensor plus images from either back, but I have yet to find any software tool that gets you close to the 60mp res.
This brings up the other issue on the 180/280, base iso is 35. These backs just prefer to be at base iso. You are going to get the best images quality from this. In my territory, iso 35 can be very hard to work with, early morning, with a slight wind and you are up to iso 100, or 200 pretty quick and many days I just have too much wind to get a decent shutter speed without blur. Here I see the 160/260 with a slight advantage in that you are starting at iso50. In theory, you can also turn on the 260 at long exposure base iso of 140 and get a bit cleaner file. (this is one of those areas I am still hoping to see some image quality improvement on).
Back to your lenses question. From the ones I have used in the field. I am mainly wide oriented. Plus once you find the hyperfocal range of your wide, for my work, I rarely need to change focus. Not true from 60mm on out.
Rod 28. Excellent lens wide open. I use the CF on mine as it does make a difference in corner noise. If pushed due to light/wind etc. I will go without the CF. This is an excellent lens across the back range. On the 180 I picked up a bit more color shift even on center, but the LCC corrected it fine. It's a dream lens and and F8 my range is around 12f to infinity with 1/2 a degree of tilt on the 160/260/180etc. This lens will flare and flare is destructive. I use mine from F5.6 to F16. F16 will show slight diffraction softness, but not enough to matter for me. Shifts, only about 7mm max, as you hit the vignetting disc that Rodenstock places in all their lenses to tell you where the Image circle limit is. It's too bas as this lens on a 260 would easily make 10mm maybe 12mm of shift. IC is 70mm Lens is big and heavy, about as heavy as a Nikon 24-70 maybe a bit heavier.
Rod 32, as good as it gets, but it's also around 10K with the CF and just too much for me. It's also a more delicate lens and many folks have had issues with the outer elements becoming out of alignment due to the mass of glass beyond the shutter. This lens will shift to around 15mm before you hit the disc. It will easily make 20mm if you don't mind cropping. Some shot it without the CF I have only shot one with the CF. Not filter friendly if you use the CF and will only hold one normal screw in filter before you vignette due to the filters. But it's an excellent piece of glass and probably has only be surpassed by the new Rodenstock 90mm SW (yellow band also around 10K)
This lens is heavy and bulky.
Schneider 35mm, one of the standards out there for tech cameras. Recessed lens board makes getting your hands on the shutter and aperture settings a bit tricky. Less distortion on center than the Rodenstocks. On a 60MP back you can still get around 8mm maybe 10mm of shift depending on the subject. Past that and you will see detail smearing and extreme loss of color saturation. This lens can have centerfolding issues on Phase Backs, especially on shifts. Most times this can be fixed by the dealer but sometimes it just can't be. Amazingly sharp lens and very light weight. Requires the CF all the time. On the 80MP backs you will see just too much color shifting even on center to use this lens. The LCC just can't fix it all. CF takes around 2.5 stops and best aperture range I have found is from F11 to F16, pretty limited but if you can hit there excellent results.
Rod 40mm, one great piece of glass. I upgraded to used one mid this year. It had to go back to Rodenstock as the lens was out of alignment on the lower right corner. (Thanks to Rod Klukas for his help here). This lens is amazing and I have just about quit using the 35 Schneider anymore. No CF needed, so right away you have more light to work with. This lens is excellent from around F5.6 to F11, and I believe Rodenstock states best results will be F8. I have taken mine to F16 and it does suffer from diffraction issues here. Shfits to 18mm on the 60MP backs, not sure on the 80MP backs. At 15mm you hit the disk inside so again you will be cropping out top and bottom if you go past 15mm. This lens is famous for a center flare issue and it will get this issue sometimes even with the sun at your back. I use a hood (Lee setup) on mine at all times and so far have not had any issues. Very versatile lens, not as heavy as the 28 Rod and bit smaller, but it's still big compared to the Schneiders. THis lens does not seem to have as big an issue with centerfolding as the Schneiders even on hard shifts. I have shifted mine all the way to 20mm and besides the top and bottom vignetting, the results are stunning.
Schneider 43mm, wonderful lens. Will be selling mine soon as the 40mm has taken it's place. No flare issues unless shooting directly at the sun. Much lighter and smaller than the 40mm Rod. I would say this lens is excellent from F8 to F16. F16 may be a push. I use the CF on mine and it does make a difference. You can expect to shift this lens to about 12mm on the 60MP before you start to see detail smearing and sat fall off. On the 80MP back I found that I was limited to only about 8mm of shift before the details were smeared and the LCC would not totally correct the magenta shifting. Still very sharp and I have taken many a great series with this lens and it has never disappointed me.
Schneider 60mm, excellent lens, IMO as sharp as the Rod 28mm. This lens is where shifting gets fun. You can push this lens to 25mm of shift and most times the LCC will totally correct the image. Not heavy, and good from around F8 to F16. As is the case with all the Schneiders I have used, they are not be best wide open or close to wide open.
This lens requires me to use a laser range finder and the DOF can get a bit more tricky. I don't have as much experience with it as I do the others but again I just don't need the focal length as much in Arkansas. I have the CF on this also, but you can get away with not using it pretty easily.
You can't go wrong with either back. However I can't see too much improvement to the 280 from Phase since the 280 was basically a push to the 180 (280 uses the same chip as the 180) but has different controller cards, has wifi etc . But you never know. Right now I feel that most the R&D at Phase is on a CMOS solution.
Got a bit wordy on this one.
Paul