Regan, I'm not to sure on the launch control as I haven't used it. IIRC I believe it is switched, as in you switch it on in the cabin, revs are then held at the set point which you adjust (say 4,000rpm), you floor it with no change in the revs, then side step the clutch and the rev launch disengages to normal throttle control. It could be fun but it sounds very harsh to me, not ideal for old Datsun's!
I'd go with Jason's, there's heaps of reports of recent failures on the newer chinese items!
Didn't MSD move there production over there recently?