Hi. Yes I did try out the KX drivers with the Sound Blaster Live card but was disapointed with the results for Hauptwerk. I then had rather a difficult time uninstalling them and reverting to the original. I got the lowest latency (15 buffer blocks) with SBLive and the "Basic" driver set 5.0.2184.1 However this did not allow support for all the SBLive functionality like HQ etc.
I eventually reverted to the VIA on board chipset and updated drivers and found for Hauptwerk the latency was much lower than using the SB card. I am easily able to use a buffer of 6 blocks with the St Anne's organ.
I also had another problem with the SBLive card in that it produced serious audio overload distortion. Hope this helps. Cheers.