Depends on what you want it for. I run one but i use it for the shift light and the rev limiter(two step). Also the best setting is the stock on the dyna and use a timing plate to go a little more timing.
If you have the bucks and some dyno time you can really tweak on all timing curves, cause you can program it. The biggest problem is dyna customer support. You will be on hold for 20 mins or longer before you talk to someone. Me personally i like it, but do not get rid of your stock CDI just in case porposes, Trouble shooting scenario. Hope that helps