What do you want to use the camera for - is it purely for walking and climbing use.
Have you considered a micro system, for example micro 4/3rds (m43). Same physical size sensor as your e620 but the pentaprism and mirror box have been removed.
I've got a m43 Panasonic G1 that I bought a few years ago. It's got a built in electronic viewfinder (EVF) in place of the optical viewfinder. It's not as good as a good optical viewfinder but much better than starting at the rear display screen (which does flip out and rotate for creative shots or selfies)
In the last year I added a Panasonic 12-35f2.8 lens, which all I carry when out walking.
The sensor of the first generation m43's like the G1isn't the greatest but the latest crop are top notch, and I'm hoping to upgrade to a GH3 body.
Used to carry a 5D and a few lenses - weight a ton. Dodgy knees made me rethink.
My G1 + 12-35, battery, card and skylight filter comes 815g on my kitchen scales.
Here's how my G1 and 12-35 (24-70 equivalent) looks next to my 5D and 24-70