Before I bought my Z950 JD I was about to buy a Scag TT. I love those mowers. The Cheetah is nice enough, but I doubt it's built any better than the 3100 after looking at them too. I kinda wish I had gone with the 3100, but dealer location was a big problem for me. anyway, the Cheetah is way too cramped feeling to me. Tiny floor board area etc. the TT was the only real Scag choice IMO. I don't mow at speeds that require the Cheetah's top end, and I could care less about speed bragging rights. I just want a mower that is fast enough to make me time and money.
Right after I bought my 950 Gravely came out with the new 400 series. That will be my next machine no doubt, and that's saying a lot, since I have been a die hard Deere man for all my equipment for many years.