Anybody successfully put a P4 or Rebel in a U2?

I love my U2, in my top 3 all-time favorites. I wouldn't mind a litte extra runtime though. I'm thinking of buying another U2 and having it modded with a new emitter, but I don't know if that has been successfully accomplished yet. I know there have been issues with the regulation and level switching in past attempts. Is this possible with any of the newer LED's on the market?

As an alternative, what about having one modded with a premium bin LuxV? Are those still available? How much extra output/runtime could I expect, if any?

Thanks for any thoughts you guys have.

I'm interpreting the silence as a 'no'...

I think it has something to do with a LuxV needing 6-7V and a LuxIII/Cree/etc. needing 3.7.

U2 + SSC P4:
http://candlepowerforums.com/vb/showthread.php?t=152464

I'm personally waiting for a Luxeon replacement that has the same vf of the Lux V. You could go with a higher bin ('WWOS', I believe) Lux V, which I think gets you another ~30+ lumens, but I don't know if that would make much difference (unless you are looking to get rid of a bad tint or a donut hole at the same time).