I did the exact same steps.. got stuck in the reboot loop once I'd installed (and forced the rest of the install to finish). Popped the battery, rd mode to no lifeguard, and the reboot cycle goes away.. and returns again if I take out of R&D/no lifeguard.

I don't know if it's a symptom of R&D mode ( my understanding is that it doesn't cause any performace differences), or maybe I'm just imagining things.. but the overall system suddenly feels speedier since doing this minor upgrade.