For a light that's used for normal flashlight type runtimes, a heatsink that just adds a big dumb mass inside to store up heat is pretty useless. What matters is if it can shed the heat as fast as it generates it - which this light is capable of, with some tweaks, without filling the insides full of copper.
The flimsy aluminum plate needs to be swapped for a 1/8" copper plate, and whatever star of your choice bonded on top. The heat transfer on this light is decent, for two reasons. One, the plate under the star is clamped down tight between the head and battery tube, which is a whole lot better thermal path than anything P60 based. And two, the outer surface of the body, where that heat will ultimately have to jump the gap to the air (or your hand), is probably double the surface area of a typical 1x18650 light. Is it now pointless to play with P60/18650 lights, too?
The only potential issue I see is possibly the driver board, though I would probably take the easy way out and bypass it altogether with a jumper wire. Oh, that and the $20 price tag... but if you already have one (I do, haven't cut it up yet), why not? (and then you can stick the leftover XB-D in a Mag Solitaire or something!) 