I just bought a pair, and I'm enjoying them tremendously. But, I didn't do a lot of comparing, except to my older Grado 225s. The 325i is certainly a very worthwhile upgrade, but I haven't heard Sennheisers at that level lately. I'm just coming back to occassional headphone use, after sacrificing my 225s to the kids, so that I don't have to listen to their hip-hop and gangsta rap through the computer.
A nice SET headphone amp from ASL is on order...