You know, I totally forgot to think about the voltage drop across the transistor.. and since the recommended Vf is 3.42v on this module, that's quite a bit more breathing room than I was thinking at first. Five ohms was a little high anyway, it was a convenient number when I was having trouble finding low-value resistors in my box of goodies. If my math is right, the "ideal" value is about 4.7 ohms... but as you had said (and I noted in another thread), we can probably get away with overdriving the LED quite a bit because of it's intermittent use. Heat is the issue in play, and our flashes are pretty short. That being said, 1w LED's go for cheap money these days and I wouldn't freak out if I cooked one over the course of a full evening of trick-or-treaters..
SO.. I may add a third 10 ohm resistor in parallel, which drops the series resistor to 3.333etc ohms. It will be getting overdriven pretty significantly at that level, but since it's a Luxeon Star, it's mounted and heatsunk fairly well, and if needed, I can grab some heat paste and slap it onto an old CPU heatsink I have lying around.
As wired, it would be pretty good for some window display or whatever at best.. overdriving it, especially since I am Underdriving it at the moment, the light output (if it remains fairly linear, which I think it does, to a point) might be a LOT higher than it is now..
Thanks for catching that! Once again, too many years away has left me a bit of a dolt when it comes to circuitry.. three semesters almost thirty years ago, way too easy to forget valuable info!