I installed my Scotts lastnight in about 10 minutes (954). The directions are basically useless, but it's really easy to figure out what to do. Only have about 100 miles of riding with it on and it is awesome! 2nd gears wheelies are much more enjoyable now that I'm not worried about finishing it with a potential tank slapper.
Still not happy about spending $400, but I think the safety and confidence improvement is worth the investment.