I have the BMS stop, bought from BMW direct, works nicely and gets rid of that annoying leg stretch you need to put the clutch right down.
Means you can move the seat back a bit, to not be co close to the throttle and brake. No problems with start/stop or normal starting, if you use too many spacers (3) then the car won't start as the clutch will be too high.
2 spacers worked fine for me, the car starts and you can select first and reverse perfectly well, both cold and hot, indicating the clutch is still FULLY disengaged.
I also have the CDV mod, but we just popped the valve out of the standard one with an allen key, easily done, than refitted it without the valve, still OE from the outside.
Great mod, really smooths shifts, especially 1st to 2nd. Worth every penny.
E63 AMG here at last!