Unless I'm mistaken, a 1W is not capable of putting out as much total light as a 5W; however, if a 1W is setup correctly, it can be made to out throw an L4 by a large margin.
I think I've seen the mod you're talking about. Someone converted a P60 LA into a pill of sorts for the P based lights. I'm not sure of how friendly the P series reflectors are to LEDs though.