I have a Dereelight 3SD in a 3P, it's great, and it is putting at least 1.2A into the LED. You do have to use an RCR123A, it won't be anywhere near as bright with a CR123A Primary.
I also have the DX Sku.11074 which is damn close the Dereelight, but not quite. It also is a little longer in the driver area, which will cause the module to not fully seat, and the bezel won't screw down all the way, unless you were to bore it out a little bit.
Too bad no one makes a P60 drop-in (that you can buy seperately) using the AMC7135 driver, because it also works pretty well on one RCR123A, not as bright as either of the above, but still pretty darn close, and having multi-modes on a 3P is kind of nice because of the one small battery.
I'm sure the Malkoff is great as well, but don't have any direct experience with it. I know for sure that the Dereelight drop-ins work perfectly in a 3P, and definitely the ones that are rated specifically for use with 1 Li-Ion battery are the brightest, and that's even comparing them to the ones that support multiple batteries (higher voltage range)