I've also wondered about the diablo and pre loaded tunes.
The DOB is interesting. I've thought about doing a DOB or Brenspeed's Throwback Paxton. But I'm becoming cheap in my older age.... And I can't see myself trying to piece together a DOB kit over time.
I just figured gears, set of cams and a tune would be fun for around $1500.
They do have the DOB stage 3 which is the whole thing ready to go. Still cheaper than any other kit.