I've got a 1996 1620 with 600 hrs on it and I love it.
It's the right size for what I am doing. I needed maneuverability in my tight wooded area and the 1620 is smaller than a 1920 that I was originally looking at. It's never lacked for power however sometimes I would like more lift capacity that the 1920 or 2120 has. I've moved about 200 yards of dirt, pulled big logs, lots of firewood, moved lots of patio pavers, brush hogged fields and more. It runs my 5 ft brush hog fine, has adequate lift capacity (full buckets of moist sand). I've put my friends 3 pt mounted woods backhoe on it and that worked well. It dug trenches and ripped out stumps for me.
I put chains on the turf tires as the plane turf's don't bite at all in the snow. It would pull my 5 ft back blade in the winter on the snow without the chains, but if I had to use the bucket to move large piles of snow it had poor traction even in 4wd (without the chains). With the chains I pull 18" dia by 40 ft logs up snowy hills in 12 to 20" of snow. It's a tank with the chains on it. Yet the turfs are friendly to the grass in the summer. I've recently added a 7.5 ft truck style snow blade to the back and it plows snow like a champ.
The Hydro drive is nice. I have a bad left knee and it was hard using my friends 1710 with a clutch so a hydro was a must have for me. With the 1620's hydro and the high, medium, low selections you can find the right ratio for the work that you are doing. And it's so nice when you are moving soil to and fro not to have to clutch in several hundred times in a day like my friends 1710. The control placement seems nicely laid out and you don't get tired of being in the seat. It also sips fuel and starts well at 10 degrees F even without a block heater.
The only down sides are trivial. The headlights are not that bright and the ROPS does not fold. The ROPS on my 1620 is about 1" taller then my garage opening unless I keep the rear tire pressure on the low side. But that isn't an issue unless I have the backhoe on it, which is rare, and then you need to pump the tires up anyway due to the weight of the backhoe. The ground clearance is good but the large low pressure hydro filter sticks down. I dented it pretty good on a branch once when I was deep in the woods and it loosened and started to leak a bit. I could not figure out why they didn't place that filter out of harms way. It dented but didn't get a hole in it or leak much and I'm just a bit more careful running over big piles of branches. I've dropped stuff on the hood and it didn't dent to easy (similar to my friends 1710 I would say).
I've had no mechanical problems with it except the zerks on the bottom of the bucket pins tend to plug up and grease will not flow into them. I remove and replace them about every 2 years (a 10 minute job). The are just in a bad spot and get muddy and full of water in my swamp.
I am really happy with it.