At first when I was was designing my control panel, I thought "Do I really NEED a spinner?" Well anyway I''ve narrowed my choice down to the TT2. I just have some questions about it:
1) If I buy the 5" Mini-Racer™ Steering Wheel, how easy is it to swap the normal knob out with the wheel?
2) What does the Energy Storage Cylinder actually do?
3) Should I go with PS/2 or USB? I've heard PS/2 is better.
Thanks in advance,
Xb0x3r 
TT2 spinner = Smart choice. Not only is the price cheaper, but it is the easiest to install, has a supersmall footprint and has the highest resolution of all those out there. And it's a GREAT product.
The wheel is very easy to swap out. You can remove the knob of the TT2 with a simple screw on the side of the spinner knob. (see my comments below on this) Then, the wheel simply pushes on (no need to tighten it... it does not come with a screw). It holds nice and secure, so don't worry.
As far as the energy cylinder goes, you don't need it if you buy the token spinner. The token spinner is heavy enough that it acts like the energy cylinder. Furthermore, it fastens to the spinner using a special type of screw set that WILL NOT damage the spinner base with repeated removal. This is very important if you are using a mini wheel.
Read more here as Randy mentions this (Randy T is the owner of GGG the manufacturer of the TT2):
http://forum.arcadecontrols.com/index.php?topic=74205.msg768004#msg768004Hope this helped!
~ DeLuSioNaL