My 1996 "Plastic" 1620 was HST, and it was a great little tractor, except for the Kohler Magnum engine. Valve guides wore out every 300 hrs. First time was less than a month out of warranty, and Kohler refused to help. Authorized Kohler dealer/repair shop said it was ridiculous to loose the valve guides with that few hours. I'll never own another Kohler.
Attachments weren't exactly quick attach, but not that bad either. Everything used the same mounting points, (so unlike Kubota, no special sub frame for the snowblower that had to be removed to use the FEL, which had it's own sub frame mount that stayed in place no matter what else you were using). MMM used the same mounting point as the snowblower, or the front blade if you had one. Basically just pull 2 pins and slide it off. Each attachment had its own "hitch", and there might be drive belts or controls to hook up, but the mount to the tractor was always through the same point.
If I hadn't moved across the country, I'd probably still be using it. My neighbor bought it and I'm sure he is still using it.