Hi - nice build idea. That will be one really bright sucker.
I am not really awake yet, so this is kind of dangerous, but I will point out the "risk areas to double check".
The DB is a nice, proven board. I have not had my coffee yet, but the Shoppe is listing boards up to 1000ma, not 1400 - maybe I am forgetting that these can go higher. /ubbthreads/images/graemlins/smile.gif
At 1400ma, the LL data sheet shows a Vf of 3 for that product, giving you a Vf for the 3 = 9 V. For the NiMH setup, you only have approx 8x1.2 V = 9.6 Vin. I cannot remember, the specs on that board, but I kind of like to have at least 1.0 V drop to play with when using a CC board.
Normal alkaline AAs might not work at all, or for long at 1.4 A draw rate. You will definitely want to have the Li enhanced ones.
Heat - If you are running this super light for only 1 minute or so, it will be ok, but if my calculations are correct this morning, you have roughly (9 V x 1.4 A = 12.6 watts) of heat to dissipate through your hand. This light will quickly feel very warm. Of course since you will be able to see everything a long ways away, then maybe it does not have to be on very long. /ubbthreads/images/graemlins/smile.gif
Last, but not least, and this will likely get me some flack, I suggest running at more like 800 - 1000ma. Reason - light output for LEDs drops RAPIDLY as they warm up. I don't claim to be an expert, but my bench experience with (mostly white) is that it is just plain hard to remove that much heat from an LED and drive anything close to that power level. The net effect is that your 1400ma spent (might) give no more light that 1000ma would after 60 seconds.
Of course, for "quick on / off", it will be fine.
Have fun with your project - and buy extra parts, something always seems to break just when you are almost finished.