I agree that that seeing "Generations" of warfare in strict linearity is very problematic. IMHO it's better as a simple taxonomy than a chronology.

OTOH, mainstream historians other than those associated with 4GW have also made the argument the the adoption of disciplined formations armed with smoothbore muskets (1GW) constituted a "military revolution" rooted in a particular time and place.

http://www.amazon.com/Military-Revol.../dp/0521479584