How about going with RCR123 rechargeables and a 3 cell bulb?
From mdocod's (what? no "I am not worthy" smiley?) Lithium-Ion page
http://candlepowerforums.com/vb/showthread.php?t=161536:
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Cell configuration: 2xRCR123
Bulb Options:
LF D26 ES-9: 7W, 98 - 56 lumen in 38 minutes
LF D26 SR-9: 9W, 126 - 74 lumen in 25 minutes
LF D26 HO-9: 12W, 160 - 88 lumen in 20 minutes
SF P90: 9W, 118 - 70 lumen in 25 minutes
G&P G90: 9W, 118 - 70 lumen in 25 minutes
G&P D26 7.4V "DX 10W xenon": 9W, 118 - 70 lumen in 25 minutes
G&P D26 7.4V "DX 15W xenon": 10.5W, 136 - 80 lumen in 23 minutes
Pathfinder P90: 10W, 129 - 75 lumen in 23 minutes
WE D26 9V: 10W, 136 - 80 lumen in 23 minutes
Pila GL3 LA: 10W, 136 - 80 lumen in 23 minutes
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It looks like you could go with a Lumens Factory H0-9 for 12 watts. That should be impressive. I'd want a glass lens with that, but you could get by with short bursts I guess with the plastic lens. mdocod rates the LF E0-9 in a 2x17500 (G3 or other 3 cell light) at 15 watts and I find that an impressive step up from my SureFire G3L or Fenix P1D CE Q5. mdocod rates the P90 lamp in a 2x17500 light at 9 watts. I find that to be brighter than the G3L or P1D CE Q5, just not impressively so.
I was going to mention something like that on your other thread. I'd recommend rechargeables to someone using an incan anyway so you won't be thinking about how fast you are going through batteries.
I can understand wanting to keep the incan. Using the LF H0-9 lamp with the RCR123's in your G2 may require multiple clicks to light. That can be kind of annoying. I'm sure someone has done this. I'll do some research on that setup. Maybe someone with experience can comment.
Lighthound sells the AW protected RCR123's for $6.99 each, a DSD charger for $12.99, and the Lumens Factory H0-9 for $14.99.
I didn't mention on the other thread, but if you do get a G3, mdocod does not recommend the P91 bulb with 2x17500 rechargeables. The brightest bulb he recommends for that setup is the Lumens Factory E0-9.