Hallo,
i have a C30/X2000 (Cree P4-WC on 19.9mm star pcb, flood-to-zoom, 18650/3xAAA) with an additional 16-mode 3.7V 1000mA driver (Atmel0713 with 3x7135/350mA).

Since i cannot replace the dummy pcb (driver has smaller diameter, 17mm<>19.9mm) i've built a small extension with a plastic ring covered with adhesive aluminum foil (ground bridge) to create more room for both PCBs. Not doing this would push the star pcb away from the body resulting in no heat dissipation.

1) Any other solutions known to fix that problem? Not sure if this is the non-plus ultra.

2) Would an XR-E R2 upgrade be the best pick for flood and throw? XP-G R5 shouldn't be that good for throw i've read (despite being brighter for flood).

3) I'm running the driver with 3xAAA rechargeables (1.2V, cheap and worn out ones atm, ~200mAh). Is there any difference between 1.2V rechargeables and proper 18650 cells when using a driver (regarding brightness)?

4) What happens with the old 1.2V rechargeables if i have a XR-E R2 running at over 900mA and they have high impendance? Will they get hot, collapse or something?

5) I can add another 7135 to the driver PCB resulting in 1.4A output. Will the R2 benefit from getting +400mA at all? Some LEDs seem to mainly change their color with only minimal gain in brightness. Is it advisable for general usage?