natem,welcome to the forum.
I have an HST, but there are a few members who have the gear drive and love it. Generally, with a tractor, you're not really shifting all the time. You usually get the gear you want and work forward and shift to reverse. When you want to go faster, you change gears, so it's not exactly like shifting a car.
The gear model CK20 is something you'll be able to get used to using, but you must clutch between shifts, and I think it's synchronized only between second and reverse. I may have that wrong but it is only between one gear and reverse, and that may be a little slow when doing a lot of loading.
You get a little more torque and horsepower, but the trade off of convenience was not worth it to me so I got the HST which is much easier since you only need push the HST pedal forward or back without clutching in between or even thinking about it.
When you're pulling something, the gear model will dig to China before giving up whereas the HST model will eventually hit it's relief valve pressure and not pull any more. I haven't found that to be a big problem, but there are times when I wish it had not given out.
The price you got is pretty good, and they're not likely to go anywhere but up.
Make sure you try each out and see which one you really like. For sure, do a little loading of some dirt or something so you can see what effort both require.
Good hunting and let us know how it turns out.
John