I've bought my Grasshopper 721-D zero turn several years ago, and i wouldn't go back to a riding tractor again. My zero turn cut my mowing time in half, and it does a much better job.
I bought an industrial zero turn, so i wouldn't have to replace it any time soon, and i like how it rides so much better than the other designs. That's important to me, as i have back problems, and i don't need to be making them worse. Also, with the front deck it's easy to mow under bushes and tree's...
DM