I tried button clutch for the first time yesterday and instantly wiped 0.2s off my BL1 XFG PB, its way faster and needs to be fixed.
The clutch right now is unrealistic. You can shift faster than would be possible in a normal road car with a standard clutch.
I have thought of a solution, though I don't know how easy it would be to implement: The clutch should have a maximum bite pressure, just like a real clutch and if you exceed that it will just slip. Therefore no matter how fast you engage or disengage the clutch, shifting will be limited by the clutch itself not the button rate.... No more unrealistically fast shifting.