When you look at any type of gear shift tractor, there are three areas to consider. When I was looking at tractors, I found it took a little digging to get past the brochure jargon and happy-thoughts to figure out what the tractor really had. And there are a LOT of different combinations.
1) Reverser. Most modern tractors have a "power reverser" which is a column mounted stalk that gives you F-N-R control without any clutching. No gear changes, just F-N-R in whatever gear you are in.
2) Gear shifting can be manual unsynchronized, manual synchronized, or power shift. Manual unsynchronized means you need to clutch, stop moving, shift, then start up again. Manual synchronized means you need to clutch, but you can shift without stopping. This is like a typical car manual transmission. Note that on some newer tractors you can operate the clutch with the peddal, or with a button on the shift lever. The button makes clutching and shifting really easy. You just hold the button down, shift, then release the button. The last is power shift where you can shift gears with no clutching, typically with a push button. The "up" button shifts up one gear at a time, and the "down" does the opposite. This is really nice if you have to do a lot of shifting.
3) Speed ranges can also be manual unsynchronized, manual synchronized, or power shift. It's all the same as above, but only when you need to change ranges, and that will depend on how many gears you have, and how you are running the tractor. The more gears you have the more speed range you have before you need to change range. So try using the tractor as you expect to see if you can mostly operate in a single range, or if you need to be changing range all the time. The more frequently you will change range, the fancier mechanism you will want. The ultimate is full power shift for both ranges and gears. You just keep pressing the button and the tractor will shift gears and ranges as needed.
I hope this helps with what questions to ask, what's possible, and what to expect. I found surprises in a number of tractors that I considered.
