To the comment about PTO work, I can tell you I have a Deere 665 tiller and the 3520 is more than enough to run it, even in less than ideal soil. I run out of traction way before power, so if it were me unless the 3720 was roughly the same price, I wouldn't opt for it. TBH, I still have yet to see one, actually. There are a couple 3120s around, a ton of 3320s and a fair amount of 3520s. If I had to do it again though, I would have went with a 4x20 machine though, just for the larger frame and stability, though the 3x20 is nimble enough to get places the 4x20 can't, so there are tradeoffs for sure.