I spent a month on the road in Serbia, Greece, Turkey, Bulgaria and more this summer.
I knew I would be shooting my friend's iconography, so image quality was paramount. On my previous trip, I shot with a D700 and D800. Some photos I wish I had shot with the D800 for the the IQ but the results were fine non-the-less.
I wanted to simplify some this trip as far as batteries, chargers and not have to remember which body was which. So this time I brought a pair of D800 bodies, the usual several pounds of lenses and all the stuff needed to support a month on the road. For kicks and grins, I brought my Panasonic GX-7 and two lenses.
For the absolute IQ, the two D800 bodies were king. However, they are larges, noisy, heavy to pack around and very intimidating when shooting people.
Most of the shooting in the streets and many of the monasteries I visited along the way was done with the GX-7 for my day-to-day shooting. It's small, quiet (no sound at all!), does very acceptable HD video and was unobtrusive while I shot so I was ignored most of the time. When I needed to wade through crowds, in other words to look "professional", I packed the pair of D800 bodies to get me access to the front of the line in a few of the situations.
Now that I'm home and have had time to edit, select, process and print, I can tell you that the Panasonic GX-7 held its own with the D800 and with the 7-14mm lens, saved the day in a couple of tight places I needed to photograph.
At ISO 3200 and 6400, the D800 and the massive files clean up well and the prints can get super-sized. Up to ISO 3200, the Panasonic GX-7 was quite acceptable, especially with some aggressive noise reduction in ACR.
Prints for my portfolio are 13-14 x 19 and size-by-side with the D800 images, the only way I can tell them apart is that the aspect ratio of the Panasonic is 3:4 and 1:1 when I shoot on "Rollieflex/Hasselblad" mode (square). For me, the ink-on-the-paper is the test for my work.
I really think I should have left the second D800 at home and took another GX-7 other than I like redundancy when I travel with a second body (my colleague's D800 bricked on his last trip to Greece a few weeks ago) and overlapping lenses just in case. As luck would have it, my wide-angle zoom AF went out on my last day so I missed a few shots, but that was minor.
IMO, I would be quite content to simply downsize to an M4/3 with 2-3 good lenses and matching bodies and an iPad and stay light on my feet. I can tell you that one body, two lenses and a pocket full of batteries (the GX-7 goes through many in a day, the D800 can go a couple of days shooting the same quantity) and a spare card with nobody raising an eyebrow because you look "professional" not to mention the lightened load was very liberating!
