I have to sincerely disagree.
I've been playing d20 products since they have come out and there is significant differences between products.
Tone, Atmosphere, Adventure Types, Character abilities varying widely from:
Mutants and Masterminds
Macho Women with Guns
If they were all basically the same there would be no need to produce a core book for each of these settings.
So I'll sit here hoping someone at Mongoose will heed my plea for a fastplay rules or "Armaggedon:First Skirmish"