I am a 2210 owner and have been pleased that the tractor does those things that everyone described above. I will be graduating upward soon but not out of dissatisfaction for the tractor's capabilities. I have a few other issues with my specific tractor but they are not problems with the model as a whole.
I'm only moving up one step to the 4110 for a little more capability in the hydraulics and the more universal true Cat 1 hitch. The only limits of the 2210s hitch, in comparison, are lift height and a bit less weight capacity. The 4110 does offer the bigger tiress which results in the lift height advantage and more ground clearance. I will still do the same amount of mowing, or more, with the 4110 and am not too concerned about any loss of agility. The turning radius for the 2210 and 4110 are almost identical. The engine specs between the two are also virtually identical. I think there are gearing ratio differences that provide for more useable torque in the 4110. Of course this means that the higher transport and mowing speeds on the 4110 will lug a little more on hills. On the low end of the torque spectrum, the 4110 will outperform the 2210 in ground engagement due to the ratios, greater gross weight, and larger tires.
The 7500 you mentioned in your original post is more comparable in size, etc., to the 4110. The BX is the model match for Kubota. I bought my 2210 as one of the first units off the production line because I had been waiting for JD to fill their product line gap. I do think they have a real winner in the 2210. My only issue was that I found more and more heavier work to do with the tractor as I learned of it capabilities.
The premium cost for stepping up to the next level above the 2210 and BX (new equipment) would be anywhere from $2,000-$3,500 depending on other add-ons. If you see any possible need for more tractor in the next three years, I would say take the step now. If not, the 2210 is a great little tractor.