Firstly, I suspect that this question is really to do with Ableton and Reason, and NOT specifically with MIDI. You might be better asking in a forum relevant to those applications.
Secondly, there's been another question raised recently regarding to changing tempo, and it was suggested there that it would be necessary to create TWO controllers, one to raise tempo, and the other to lower tempo.
Note part of the answer there, a change of 1 will be not noticeable, you will need a much larger number to be detected. However, the resolution of the controller is clearly nothing to do with MIDI.
Geoff