Thanks for the reply.
My situation is a little different from most in terms of dealers and trying out gear, as Port Hedland is a looong way from civilisation. Downside is I'm always going to be buying gear I've never tested personally, upside I guess is Australia's northwest is a pretty awesome place to photograph. It does make me more reliant on online opinions, though, compared to those who live in the big smoke.
Thanks for the links to the 28mm/tech camera comparison - I've done enough reading around that I'd previously found that page. The links don't work for me - just a 404 error. If you can repost, that would be great - I would really love to see the difference between those 3 lenses.
Part of the problem with the Mamiya 35mm seems to be field curvature, if I'm not mistaken. I'm wondering how much the corner problems can be improved with focus stacking. After reading just about everything I can on the net, I went with the older 645AF (ie. non-D) version as I haven't heard anyone talk this lens up. The reason I didn't just stick to the 28mm and crop is filters - the 35mm has my favourite size, 77mm, and the 28mm D has - nothing (much). A lot of my photography (such as slot canyons with running water) needs a polariser and an ND stacked. By the way, I asked the guys at Lee about filter holder mods for this lens - apparently they're selling a 'bespoke' filter holder for the 28D thru Phase dealers?
I'm glad you sound a bit positive about the 45mm. I've got the D version of this lens. I hear mutterings about it being pretty good (or OK) for landscapes, but there's really very little data about it on the 'net.
I'm very tempted by the tech camera idea, as ultimate image quality is what I'm after at the end of the day. My concerns are really about usability - mainly focusing. How sharp is the focus really going to be (compared to viewfinder or AF on the DF)? If your colleagues could hurry up and bring out the CMOS back with proper live view, I'd 100% be shooting tech. But at the moment, I worry that I'd be shooting more slowly with the changing light and possibly giving up most of the optical sharpness due to focus difficulties.
I don't have any useful tech camera experience to base my opinions on - though I do have a Sears and Roebuck 4x5 so perhaps I can use the P65 with that? (with some gaffer tape to hold the back on as I doubt P1 make an adapter).
Anyway, thanks for the info - and if anyone else has more data points to add they'll be greatly appreciated.