My only experience with an HST is on my riding lawnmower, and I hate it. It is set up with the rocker style foot pedals, and the reverse is hard enough to use I end up pulling up on the forward pedal with my heal to go backward. When spending an hour or more mowing, I find having to hold the pedal to go forward annoying. Noise doesn't bother me, cost is always important, both purchase and on going. I have been surprised how expensive it will be to get into a tractor that will do what I want. In the end, when talking about a 20k to 25k machine, if the $1,000 option makes it better, I would do that.
If you have an HST that is easier to use than mine, I can see how it would be nice for tight loader work, like cleaning out stalls and such. For mowing, I imagine if you are changing speed a lot that the HST would have some advantage. I can see it being easier to slow down when coming to a turn. My back pasture is weirdly shaped, so there are some sharp turns when mowing.