SASless, I'd say you're "unloading" the rotor, or reducing the power required to maintain rpm. If you then take that into the energy/power formula, with power reduced, time to decay will increase. So the technique does reduce the decay time.
Of course, like anything else it isn't that simple. You also want to control your speed, so once you've pitched back, you may have to pitch forward to regain speed. The pitch forward will have the opposite effect. Not a problem if you have a lot of altitude, but low level this can complicate things.
I'd just use the recommended technique for your type.
Matthew.