I got the 7" wheel with my TT2 and it's really great. Surprisingly heavy and sturdy feeling actually. Before I got it I was planning to build a slanted panel to mount it on because I figured a horizontal wheel wouldn't work but turns out it plays fine mounted in one of my less-used button holes.
The first game I tried it with was Pole Position. I've NEVER been able to play Pole Position using a mouse, trackball, stick or any other cobbled emu solution. You can SORT of play but it's an exercise in frustration. Using the 7" wheel with the dial sensitivity set to 11% this game is ARCADE PERFECT. The control is stunning, especially if you've played a real one recently. Finally the car goes where you point it. Of course you can't quite slam the wheel around like a full sized bolted version but the 7" is small enough that you don't really need to.
Road Blasters is another game that the TT2 wheel finally allows you to play decently. 17 sensitivity feels about right to emulate the range of the RB 270 optical wheel. Super Sprint works perfectly at 22 sensitivity although you do miss banging around that huge wheel in Off Road. I want to try APB but I'm waiting to find a real machine to use to judge what sensitivity setting it needs.
To install the wheel you just pop the knob off the TT2 and slide the wheel on the shaft, and weight and friction hold it in place perfectly.
Definitely recommend if you're into optical wheel driving games.