I'm with Mike on this one, but you are comparing 3 different category planes. The inspire is a 700 sq.in plane designed around a YS63, while the Showtime 90 is a larger plane designed around the Saito 125/YS110, and the Mayhem is basically a 3D trainer, specifically hovering and harriers, but doesn't fly precision nearly as well as the ST or Inspire.
I have the Inspire and maidened it today and my first impression was that it is my new favorite plane! I also have a timeshare on a Showtime90 with a Saito 125 on it. I haven't flown it, but my buddy says it is rock-solid.
IMO, leave the Mayhem out of the loop and decide between the two...