Chris, thanks for elaborating. Very useful information, and since I've been keeping up with your work for many years (I still have your first edition "The Backpacker's Handbook" and "The Advanced Backpacker" both of which hugely influenced my walking) and find that we share a lot of similar interests and ways of seeing both walking and photography, the advice is particularly compelling. (I also really like Ryan Jordan's take on photography and his photographic style).
I, too, don't have the money to experiment! That is why it is taking me so long to decide... I don't want to make a mistake! I've been looking for a DSLR replacement since August 2009 when I hiked in Canada using my Ricoh GX200, which was adequate, but as you bring up, the sensor was just too small... so many low light photos came out way too noisy at relatively low ISO (anything above 400 was unusable). I thought the GRX might be the answer and I really like the system, but startup and focusing are slow (I didn't buy the 50mm fixed lens because its focusing is awful, especially in low light. though it has a full-sized sensor) and, as you mentioned, it doesn't have a full-sized sensor zoom unit yet. I'm hoping that Ricoh will soon begin to take advantage of the GXR's unique system and to bring the prices down. At this rate the system is just not selling very well because it is so strange, the units are too expensive, and there are too few options for serious photographers. Each unit is like buying a whole new camera. I simply can't afford that.
When I get on the trail one of the problems I have is that once I get my camera out and take a few shots I get lost in the photography and forget about the time. I'll spend hours in a patch by the side of the trail, taking images of minute scenes, often ending up on my stomach or back trying to fit the camera into odd angles and viewpoints. I can easily take up to 200 images in a day (and end up having to give up the walk because I lost too much time taking photos!) even if every one of them is carefully composed and considered. Photography is part of how I express my love affair with the natural world, and so I need a camera that works very naturally with my hands and eye, but that I can also control according to my needs. My favorite camera before I went digital was the all-manual Nikon FM2, and I very much miss its simplicity and and the complete dependance on my knowledge of light, shutter speed, and aperture to get the images I wanted. I wouldn't go back to film because of the great expense of developing film and the inability to see what I just photographed, but part of me dislikes the loss of complete control in electronic cameras. I feel like I don't really understand cameras anymore and that there is so much inside the modern digitals that I'll never really master their use. I spend too much time fiddling with menu's and controls, rather than focusing on the world around me and trying to capture what I see.
I'm going to stop by after work tomorrow and once again take a serious look at the Nex 5. I was at the camera store today holding it and trying it out. I need to do that a few more times to see if it is what I'm looking for. There's a very good chance that it very well might be.