never owned HST but sounds like it serves many very well here. after all, this is a compact tractor forum, & HST sounds like a good match for small/mid sized tractor use. there's a reason most larger utility tractors (M series, etc) are gear driven power trains for some of the reasons stated above
driven manuals most all of my life, fortunately no knee etc issues, my hyd shuttle on my 12x gear unit to me is the best of both worlds. (all gears are synchronized)
glad the HST is a good fit for many members here as well, regards