I agree 100% that its the glass. I switched from Minolta to Nikon back in the film days, mainly for the quality glass (and also that some thieving lowlife decided that my Minolta body and glass needed a new owner). Now, with 35+ years of collecting fast, high quality Nikon glass I have a huge investment in the choice I made when I was a young man. I am still very happy with that decision.
However, as the years march by, I sometimes resent carrying a 30+ lb. camera bag with a couple of DSLR bodies, a few lenses, flashes, remote triggers, tripod, etc. The steeper the climb, the more resentment
.
I'm not quite ready to abandon my prized Nikon glass, but do appreciate the quality of the Olympus. It's great that it has worked so well for you.