You will be able to handle it but will need to watch about the weight of the cutter pushing you on slopes at wrong angles I use 64pto with the LP plainsman 15ft and a lot lighter tractor but having it set out wide at the tires helps a lot when on uneven terrain.I have a 12 and a 15 weight is around 1,000 difference,where I can't run 4mph with15,neither can with 12. Guess what I'm saying your going to need drop a gear anyways. I'm happy with running a tad slower get a nice cut and not beat me and the equipment up over running flat out with a 8ft ,bouncing out the seat and it not get everything. If your trying cut down as low as it can go in tall thick grass,like a lawn mower 100hp pto will be about right to keep any kind of speed up,me and my brother tried and both was in low 1st but it pulled it threw and he has 10more HP but set about 6inches was able roll about 4.2/4.5mph witch was a comfortable speed and ride" even better in his he has air ride". You going to be able get in and around things with bigger cutter? I just mow mainly open pastures and ROWs why went with the 15 but my 12 is a flat deck,almost went with a 12batwing this last time but I said if it gets to bad I will just scoot over on the already cut area. I see the added 3ft cause mowing couple hundred acres but on the smaller ones your shaving off some time but not a whole lot.