Hi Sean nice pics
Did you go for the copper heat sink option? If you did it will help a lot with the run time, provided you use enough quality thermal paste between the interfaces. Most thermal pastes are around 7 - 10 Wm-1K-1 and although better than air, they still limit heat transfer. So if you want to improve the overall heat sinking and run time, you could try using indium foil instead. I also prefer to look after my diodes and stick to shorter run times - generally if I feel the head of the host starting to get too warm I switch it off and let it cool. With this host and good heat sinking I would think you should be able to get a 30 second on time, just remember to let it cool properly between runs. As Paul mentioned the 405 diodes are the most sensitive and react badly to current spikes and heat, often dying with no apparent reason.
With regard to the driver will you be getting the V3, which appears to be round, or the V5, which was the rectangular buck/boost from Dr. Lava? I have never used the v3, but the V5 is a very good driver. You use one battery for boost, if you are using a diode with a higher Vf than the cell, or 2 batteries for buck mode, if the diode has a lower Vf than the two cells. In this build it looks like you'll need 1 x 16340 to run in boost mode with the V5.
Alternative drivers which would also work are the micro boost, which Jayrob also mentions, and the mini X-boost from laserer. To be honest I have a preference for the X-drives as they have an exceptionally stable output and essentially no spikes on startup, they also have a gentle ramp up to the desired current. I also have a SO6J build in a Sinner V1, with X-boost, which I built back at the start of 2013. It gave 800 mW with a G2 and is still going strong.
Good luck with the new build and if you need any help feel free to shoot me a PM.:beer:
