Here's an interesting comparison I made a few weeks ago, just checking some things on my office scales: Canon 5D Classic with 24-85mm f3.5-4.5 lens (non -L and one of Canon's lighter lenses): 12 very good megapixels, usable ISO 50 to 3200, focal-length range 24-85mm, fastest aperture f3.5. Weight: 2 lbs., 14 oz. Olympus OM-D with Panasonic 20mm f1.7, Olympus 45mm f1.8, and Olympus 14-150mm f4-5.6 lenses plus Olympus E-PL1 body with VF-2 electronic viewfinder for backup. 16 very good megapixels (OM-D), usable ISO 200 to 3200 (perhaps more), focal-length range 28 to 300mm equivalent, fastest aperture f1.7. Total weight: 2 lbs., 14 oz. I've been having some problems with the OMD recently. This, for me, is what makes it worthwhile to stick with the system.
Yup! With used full frame cameras coming down in price at only a few hundred US dollars, I've been thinking about getting an old one, a 5D specifically. I can never justify it though. Mainly because it's getting pretty old tech-wise (5D), and I don't really need ANOTHER reason to buy more lenses. Size though has me spoiled. I've considered selling my µ4/3 gear and getting a few primes, and a 6D. The mainly reason I don't: size. I carry 5 lenses and camera body in my everyday bag- with not really noticing that I'm carrying that much. If I did go the FF route, there's no way I could carry that many lenses in my bag- well I could, but it's would be quite a bit heavier and I'd have no room for my lunch in there. Selling everything would also be a bit of a pain, and a lot of the equivalent focal length lenses I'd go after aren't as good as most of the µ4/3 lenses I have now.
You might consider 14-150mm to cover all, and pick one of 45mm 1.8, 12mm 2.0, or 20mm 1.7 for low light.
I sold my 5D once I confirmed that my G5 produced better quality images. After shooting with a G5, it's tough to work with 9 limiting focus points and no face detection on a 5D. Flash, on the other hand is something that is not yet perfected the way Canon and Nikon have done with TTL.
Small size and low weight were the points that got me interested in OM-D. But the killer image quality was the deciding factor. Why would I not get a camera that's smaller and better than the Pentax K-5?
And having now had a chance to play with a 36R on the OMD I have to say it is a really impressive system.
That's pretty much the same comparison I made when I got my E-M5: Nikon D7000 + 16-85/3.5-5.6 weighs the same as E-M5 + 12-35 + 17/1.8 + 25/1.4 + 45/1.8.
Check me on this, but I think that Minolta may have invented it, but did not implement it. Olympus bought usage rights and were the first to put it out in a camera.
