In reply to Gob_Stopper: I have an OM-D E5....and a Lumix FT1 so am a bit qualified to answer this one!
I bought the OM-D by chance as a friend was selling it, but I'd already decided my lumix was lacking in one department - it didn't do Aperture priority, so it was essentially impossible to get any sort of shallow depth of field shots. The OM-D gets round that problem, and benefits from some cracking lenses - and let's face it, lenses make the difference when you get over 12Mp. I've only had it 3 weeks so am still learning it, but it's noticeably bigger and heavier than the lumix, but about half the size/weight of a full-frame DSLR. It fits in the map pocket of my waterproof or cargo pocket of trousers with the panasonic 20mm pancake on quite happily. Although it's 'weather-sealed', lenses aren't necessarily, so bear that in mind. The lumix is definitely a 'take on the back of your rack' camera for on-climb shooting though - weather-sealed, no external moving parts like an external zoom, and an easy to clean lens. I think I'll use my OM-D for shots of other climbers and landscapes, but take the lumix on multipitch climbs for shots of my partner and whatever else I can take 'on route'. Battery lasts well on the olympus - with the v1.7 firmware the image stabiliser gyro doesn't spin hard all the time, so I got a 5 day weekend (430 shots) out of it easily the other weekend. Most of the shots in my gallery were taken with the lumix, I've not got any from the OM-D in yet.