The Sony NEX series is intriguing, I would be the first to hop on board if it weren't for the ergonomics and paucity of lenses. The Sony feels a bit akward with bigger lenses, which wouldn't be so bad if the lenses were of a higher caliber. I will be the first to acknowledge that I have serious camera lust issues, but I have so far held off purchasing one of the newer offerings of Sony, Panasonic or Olympus.
The Sony, because of the sensor size, would appear to be the best performer, but the selection of lenses is limited and from the testing I've seen, rather mediocre compared to other lenses tested. Now, lens tests aren't everything and certainly, in the hands of the capable photographer, any decent camera can be made to do wonders. But the difference between the lenses offered on Olympus and Sony seem to be worlds apart in terms of vignetting, barrel distortion and overall performance. The Olympus cameras have smaller sensors and do not perform nearly as well in lower light - but the video is excellent and the JPEG quality might be better.
And herein lies the rub - when thinking about cameras, think about the system you will purchase. What systems will be around in five years?? The good thing about DSLRs is that most of the Canon, Pentax or NIkon lenses work with most DSLR bodies (the caveat to this certain lenses will only work with the higher-end lineups). What will the future of the m4/3rds or Sony system bring? Because while bodies may come and go, you want to keep lenses. Good lenses are often far more expensive than the bodies. Re-investing in a new body and new glass every few years gets darn expensive.
Finally, on the entire backpacking subject, what is good enough? How much money do you sink in a system? How important is photography to your trip? Is it the point of the trip itself or does it serve as a reminder? I struggle with these questions. My P&S cameras do not produce nearly the image quality as my DSLR did - but then again, I actually use my P&S cameras while the DSLR often sat in the pack. Oh, the torment.