I own a 576xpw and a 7910 so I feel like I can compare fairly. The 7910 got a 13.5k coil in it and runs faster in 28 inch wood, but the power increase is not enough that I get much more done at the end of the day. The tanks last about the same in both saws, but the 7910s is bigger and guzzles gas. The HD filter seals better then the husky (i grease the husky) but it needs to be cleaned more often. 7910 oils better.
The 7910 has bucking dogs on it, they are not great for falling (but not bad enough that I spend money changing them). The clutch cover seems to clear better on the 7910, but, the 7910 needs to get tuned more and starts harder. 576 doesnt really ever need to be touched and starts insanely easily. I like the choke set up better. The 576 is easier to change the bars and chains on, the Dolmar chain tensioner is much fussier. I cannot tell the difference in how smooth they are though. Both feel the same to me. When you think about the extra gas and oil you carry with the Dolmar (not a lot, but noticeable), they weigh the exact same.
The 372XT feels like a harder starting marginally lighter version of the 576. I really cant tell the same running other then the 576 being a bit more forgiving torque wise.