I just put on the KB. It is not a DD, but the boost is only there when you put your foot in it.
I am 100% sure that I could put a KB on my girlfriends stang, and she would never notice.
I guess what I'm saying is, that the blower will not shorten engine life, driving it hard will. The down side is, that driving it easy with a S.L. of power under your foot is not easy.
I would vote for the KB because you can get the advantages of the extra power without having to run the RPMs up so high.