[Workaphobia]

All I did last year was add a small deadzone - I forget if I scaled down the other values outside of it to zero or not - and implement a parabolic or sinusoidal curve instead of a linear one. The drivers liked the sinusoidal one the best, but there was a lot of room for improvement.

Try experimenting with different curves, and adding joystick buttons to increase or decrease the speed by some factor is not a bad idea. Make sure your drivers know that this process is mostly trial and error, so it's up to them to communicate which system works best for them.