We have a MS250 and a MS180. The 180 is noticeably lighter to hike in with, sometimes even ride with, which I wouldn't do with the 250. It's also noticeably better on gas so lightens the load again. On the 180 I use a Powersharp bar/chain which is awesome. For sure, I'll take the 250 if there's a lot of big cutting to do, but the 180 will do pretty much anything if you take it slow. A great little saw. Pic is the 180 on the biggest log we cut out for GSM.
Sustainable will be around forever.