Well I spent a little time last night with my WF 606A from DX, my newest one with the Q2 in it.
My older black one with a P4 pulls about 1200 milliamps from 2 eneloops, and the newer silver Q2 pulls closer to 1600 milliamps. Odd, I expected them to be the exact same electronics, but perhaps my first one has circuit problems, or is an exceptionally low forward voltage P4. Despite those differences, to the naked eye the output seemed very nearly identical. The Q2 had a warmer tint, the P4 is a colder led, but that was about it.
So, I think you ought to make your decision based more on the color you want. (the body color) Yes, a Q2 should be the better choice, but in this case at least, it just isn't much different.
I still like this model light quite a bit and it makes a nice little CR2 clicky though I haven't tested my newest one in that format. I have bought and gifted or resold about 8 of these lights now and none have let me down. The lone example was one my daughter left turned on face down that got quite hot and seems to have reduced the output.
The sku 900 is a nice looking light, but I can't imagine buying a Lux led at this point, and you are right I don't see it coming in stock any time soon, if ever. The only other nice option I see would be the Liteflux model, sku 12064, but that is 48$, I doubt I would spend it personaly, would rather spend the money on a single cr123 Fenix or something.