The 261 is a really nice saw, and I'm glad I got one. But I didn't start mine all last year; I used my 046 / 20" at all of our firewood events because I am usually the go to guy when we get into bigger wood. I think when I get older, or as a friend at work put it, "older, older", I will be running it a lot more. Don't know why on earth they think I'm already "older"; I try to convince myself they are just generally "less mature" than I am.
I did switch to the 16" 3/8 because like another poster noted, all my others are on 3/8, there's a lot more useable tooth there to work with if the saw will pull it, and I don't have to change out grinding wheels all the time. My bar needed to be replaced on the 261 so it was a good time to step up to 3/8 and try it. The rpm's in the cut definitely dropped when I went to the bigger pitch on the same size bar, but not that badly.