I'm from the same scenero as you are now. I had a 52" Husqvarna 27hp riding mower with a mulching kit, that served me fairly well before blowing the pinion gear, with no preplacement parts available. The Husq. did seem to handle our 25* slopes but with a lot of apprehension. And it would actually climb those slopes straight up. No fear of a flip-over.
We replaced it this year with a 48" Kubota 26hp ZTR with the muching kit. Mowing time did cut about in half. The 'Bota will not climb the 25* dam banks, and I am not at all comfortable in mowing with it sideways on those slopes. The 'Bota also handles deep grass/weeds much better than the Husq. Both machines had trailer hitches, so pulling a cart etc. was the same.
Turning with leaving a mark on the lawn is a problem with the ZTR. I'm sure it's a matter of learning to drive it better and slower. That thing simply wants to 'GO'. But turing around is a 1-horse operation whereas wtih the Husq. it was a 3 or 4 type turn. And we have many trees and flower beds. I don't drive either type with one hand, although that's easy enough. It took about 5 minutes on the ZTR to adapt to the paddle-type steering; no big deal at all.
My recommendation to you is to follow your best judgement. You won't be disappointed either way. I'm satisfied with the give & takes on the ZTR vs tractor type mowers.