Actually the fact that the MS310 has the "plastic" case (actually 'glass-filled nylon) really doesn't bother me. Glass-filled nylon is actually pretty tuff stuff, and as long as the saw isn't abused, it really shouldn't make any functional difference. Especially not for a weekend (and occasionally weekday) warrior like myself.
What's more important is that the saw is powerful enough to run a 20" bar with full-chisel chain, but at the same time I don't want to buy more saw than I'll ever really need. To me, that's a waste of money that I don't have. Another reason I'm considering a lightly-used saw. The other issue is that it needs to be a brand where there is a local dealer so that I have a ready supply of parts when I need them. If I sell both my 041's and buy this saw, it will be my only "big" saw (over 16") unless I can pull a miracle out of my arse and get the parts I need to fix the Super XL. The choices I have for "local" dealers leaves me with Stihl, Echo, Husky thru the Rural King (parts and service questionable), and Tanaka.
Looks like I might need to swing by the Echo dealer, pick up a brochure and check out the selection.
I just know that my 041's, tho they are wood-eating monsters, are getting a bit long in the tooth and parts are getting harder to come by. But there is still some interest in them, so I figure that this might be a good time to sell them (before they become basically worthless), and get something with close to the same capabilities, but lighter and new enough that it will be easy to get parts for the foreseeable future.