The Jinma/Farm Pro use a sliding gear transmission. This means you are acutally moving the drive gears, disengaging one pair and engageing another when you move the lever. This is done by moving a bar or rail that has a fork attached to a pair of gears. The shifting will get easier with time as all of these components wear in, but it will never shift like a constant mesh tractor. If the TAFE you looked at was a CUT it is LG same as Farmtrac, and they are actually synchromesh, like in a manual transmission car these tractors are not in the same class as JINMA or FarmPro as you noted they are more than twice the price of the 2420.
Constant mesh and synchromesh transmissions have all or some of the gear sets running together constantly, with a collar sliding on a spline between two sets of gears, this collar is moved by the rail and fork. A cog with beveled teeth on each end of the collar connects one gear set or the other to the shaft causing that set to drive the vehicle. Synchromesh adds a metallic clutch that rides on a cone that gets both the collar and the gear spinning the same speed before engagement. This is used in automobiles so you can change gears without grinding while in motion. the same is true on tractors although this ability is not near as important as you tend to select a gear and work in that gear rather than start in 1st and work your way up.
Most all Chinese tractors are sliding gear design, it is the lowest cost, and it has the fewest number of components so tends to be more reliable, the disadvantage is shifting is a bit more difficult, especially when new.
The KM series KAMA tractors have constant mesh transmission design and tend to shift much easier than Jinma but these start at 45HP.
The 2420 makes a great little brush hogging tractor, as Greg says, if you go with a 5' brush mower (it will pull a 5' for light "pasture clipping" operations) get a light duty (light weight) one and keep it close to the ground in case your tractor may tend to want to do wheelies when you let the clutch out. We ususally sell a 4' with this tractor, but have a few customers running 5' successfully, If you cut your grass before it gets much over a foot tall, you should be find. If the grass gets too tall, dont take full passes or you can just slow your ground speed to keep the engine happy.
