Toro help please

Hello everyone.. I'm new to the forum and I need some guidence before I pull the trigger on a new mower... I have about 1.5 acres of what I call a country yard... by country I mean the yard for the most part is level, but it has some bumps in it.. but the most important thing to note is that along the entire length of our front yard we have a ditch... I'm guessing the ditch is 300 to 350 feet long and about a 20 degree ( that's just a guess ) pitch... for the past 14 years I've been using a snapper 14 horse lawn tractor.. well old red finally died on me and now I have to buy something new.. my original plan was to just buy another snapper tractor... my old one had a low profile, but the new ones all sit much higher and that concerns me when I'm on that ditch.. even with my older low profile snapper I would throw all my weight up on the side of the seat when I was cutting the ditch.... since I didn't feel the higher profile lawn tractors were safe I decided to look into a ztr... reviews I've read for the Toro ztr's have been pretty good... I'm currently trying to decide between 3 different models... two of the three have 50" cuts... one of them has the two bars you use to control the mower the other 50" mower has a steering wheel, yet it is considered a ztr tractor... the two models are SW5000 and SS5000. The third model is also a steering wheel ztr tractor, the SW4200. My questions for you are: would either of the 50" models be safer on the slopes of that ditch because of the wider stance and bigger tires, or will it be more of a hinderence because it is heavier... also, I have read that the ztr tractors ( ones with steering wheels ) do better on slopes because you're actually using the front wheels to guide the mower... is this true... I'm looking at spending at least 3 grand here and I don't want to make a 3 thousand dollar mistake.. any guidence you could offer me would certainly be appreciated... oh, btw, all three mowers use a toro v twin engine ( I believe 708 cc ). Again, thank you in advance for any help you throw my way...

Roland

Toro help please