Hey Dave! I'd like a single-output regulated 500+ lumen OTF neutral to cool drop in for my stock SureFire Z2 running on CR123a primaries (about 1.5 hour run time) or Tenergy LiFePO4 (450mAh) RCR123a rechargeable batteries (about 20 minutes run time). The Z2 will be paired with a handgun. What would you recommend? Thanks!