There's nothing wrong with the drives, I just prefer the separate pumps and wheel motors. I really don't care for the 3400s I have on the Z master not that they don't do the job they just make to much dang noise, they whine to much. The gravely 36" doesn't have the integrated drives if there the 3100 either so don't be fooled by that.
I think the regular price on the 36" gravely like $7999 so the sale price isn't bad. The Grandstand is $7495 so it's a bit cheaper at regular price. The Gravely is also a bit heavier than the grandstand and has a smaller gas tank along with a bit lower BTS. The Grandstand would cost more than the gravely but you get a 5 year 1200hr warranty not a 2 year and to me that could save you a bunch of money in the long run.
If you want the gravely and you like the price go for it, it's a good mower. I'm using 2 of there ZTR mowers, A Pro turn 272 and a Pro turn 148 and they both do a good job but I don't think I'd go out of my way to buy either :laughing: