Hey pb,
Looking at this from another angle, I'd like to say that if you're considering a saw of that weight, you can't go wrong with a Stihl MS660 (actually <i>lighter</i> than the 385 by a tenth pound or so). Neither vibration nor filter cleanliness are a problem, at all, with that monster.
They say a stock PS7900 will just about cut with an MS660, and my experience has it that may be true, even on a 20" log. But putting a 36" bar on the saws and using every bit of it would very likely paint a different picture. If that's what you've got in mind you might want to investigate a little further before making a decision.
Glen