When we bought some extra property, the previous owner used a JD790 to remove some junk that had been left there. As I watched him I thought how great it would be to have a tractor with a FEL. But now I think back about him trying to get the stuff on a trailer which required the tractor to be moved in slowly and repositioned using the DT vs how it is with the HST in night and day.
For mowing in an open area, probably not much difference. Otherwise, the HST is much easier and faster. As you see almost no one complaining of problems with the HST, I would assume the reliability is pretty high. The PTO HP trasfer is so minimal, that if that is the difference, you probably should look at a 3400 anyway. I'm sure there is a cost difference, so only you can decide on that.