I found a m43 system offered the right balance of image quality and packaging for me. FWIW, my typical backpacking kit is an Olympus E-PL1 (with VF-2 viewfinder), Oly 9-18, Panny 20, and Panny 45-200, all in a ThinkTank holster bag. That seems to cover everything I need, in a relatively light package. From your list, a T3i with equivalent lenses would be bulkier and heavier, and I'm quite happy with the IQ I'm getting with my m43 system.
Here's all the currently available m43 bodies and lenses. GF3 should be listed soon:
http://four-thirds.org/en/microft/body.html
I think you need to make a few decisions:
- Do you want dedicated manual controls, and how many?
There's a lot of variety of control interfaces between all of the m43 bodies. I think the DPR full reviews do as good a job as any site in discussing the differences, but you really need to handle the bodies to see what works for you.
- Do you want a viewfinder?
If so, skip all the models that don't offer the possibility. Also, consider the price of the VF-2 electronic viewfinder when looking at PENs. The VF-2 is great, but it's not cheap.
- Do you want to stabilize any non-system lenses?
Panasonic stabilizes their lenses (but not all of them), not bodies, so if you want to stabilize an adapted, non-m43 lens, you'll have to use an Olympus body. Also, a stabilized Panasonic lens will probably work better for video than relying on Olympus' "digital video stabilization".
Panasonic bodies definitely have an edge here. I find my E-PL1's video is fine for my uses, but the file sizes are huge, and there's little of the control offered by something like a GH2.
I'm sure there are others, but those came to mind from the start. If at all possible, get to a shop and try some bodies out. You may decide that a certain spec sheet is perfect, but realize that body just doesn't feel good in your hands. I wouldn't worry about getting a second body until you decide on a primary one.
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