Alright, so I tested this Wiiwheel build and reseted all values between each run/each settings adjustments as you recommended.
1) About the remote (wiiwheel) positionning: the controls are responding correctly as long as the top of the wheel is a bit farther away from me than the bottom (think like the angle of real car steering wheel, or like accelerating with your other control scheme). But as soon as this position gets slightly inverted when the top of the wheel is closer to me than the bottom (like pointing a little more to the ceiling or like braking with your other motion control scheme), then the right/left controls becomes very snappy, similar to the problem I had that we talked about earlier in the thread. As if when a certain gyro axis value gets in a negative numbers, the controls lose any kind of center dead zone. Then, just tilting the wheel forward again in a more natural position, everything comes back to normal. I have a tendency to play with the wheel straight up to be able to use the full range of the left/right axis, so sometimes if tilting it backward just so slightly, it messes up.
2) Also, not so much of a problem than maybe an adjustment: I feel like both the sensitivity and deadzone values could benefit from a bit of a re-scaling. I find myself fiddling between 5 and 20 on both (lower end) to have smooth controls, but I think they could benefit from having a little more incrementations in this range. At the opposite, I can't imagine someone using values above 60 (upper tier) on those as it become really touchy and snappy with the smallest of remote tilting. So I'm wondering if you could take all the range between let's say 0 and 50, and scale it back to 100 (0 still is 0, inexistant 5 becomes 10, 10 becomes 20, etc, and 50 becoming the new max value of 100) That would give more needed room in the lower end for adjustments. For sure that's only my opinion, I don't know if you received opposite feedback from other motion controls user...
I tried my best to make it clear, just ask if you need something, happy to help