In my opinion, a zero turn mower is made to cut grass. Its sole purpose in life is to cut grass. It isn't meant to also plow your driveway, haul dirt in a trailer, move rocks or till the ground. It cuts grass and it does that quite efficiently and quickly.
You can go as slow or as fast as you like. As in a car, you don't have to move as fast as it can go. If you hit a bumpby patch .. go slower. If you have slopes, just be smart. It is not that hard to learn to control the machine --- just some practice. It is much much much easier to get good on a zero turn than to get good at golf!

I will always have a zero turn to cut my grass. Get as best a machine as you can afford, maintain it and you will be in great shape for a long long time.
The critical things I have learned going from the suburbs to acreage is to (a) get the right machine for the job (b) get as commercial of a machine as you can afford and (c) maintain the machine as per the manuals. Anything else just seems to create problems, wasted time and extra money.
Good luck.
MoKelly