I've been an E-3 owner for the past 2.5 years, enjoyed every single moment of using it, loved all its features and image quality, loved all my lenses (12-60, 50-200, 8mm..etc). I seriously love them all from bottom of my heart and I've been producing great looking pictures.
Have been travelling a lot, mostly doing long 4-8 hrs day hikes in the US (Utah, Yosemite..etc). The camera and lenses are...heavy. E-3 + 12-60 + 50-200 in the backpack, possibly a tripod (usually I don't bring one unless I know I'll be taking epic shots in advance) and all the other goodies = a very heavy backpack for a 4+ hours hike up/down hill, esp on summer days.
Have been thinking a couple times to switch to m4/3, but eventually didn't due to various edges that the E-3 has over any m4/3: max shutter speed, optical VF (i may be able to give this up as the latest EVF seems pretty decent), tons of bracketing modes, weather proof-ness, and most importantly, the large aperture lenses (m4/3 ones mostly start at F3.5)
Still, it's heavy..! It's going to be much, much easier to hike long hours with a m4/3 body+lens than with the E-3.
Plus, I can record video with some of the m4/3 cameras, whereas with the E-3 I need to bring my Panasonic ZS3 (pt & shoot) with me (usually kept handy in a camera bag attached to my belt) for taking 720p videos (Yes I take lots of videos during my hikes) So I always end up bringing 2 cameras.
I don't think I can afford a m4/3 body + all the new m4/3 lenses, without cashing my entire E-3 system/lenses collection.
So what do you guys think, go micro or not? I know it comes down to the "feature set" that I can/can't live without, but still, I can't decide. Any insight/suggestion/advice will certainly help a lot!