Optik49, I am considering getting one too, but in doing a lot of reading on the rechargeable 123's, I get a little nervous. Are the protected ones considered pretty safe? How safe compared to normal NiMh AA's for example.
From what I've read here on the battery forums, I believe the newer chemistry of lithium rechargeables, LiPO4, will not release oxygen if damaged or abused. This prevents the batteries from venting flammable gas, which does not happen very often with regular lithium batteries, but can. The downside is less overall capacity, but unless you are using the light in a situation where you are needing every last mAh and/or can't carry spares, you just charge them up again. There is no memory effect when charging lithium batteries, so you don't have to wait till they're run down - just charge them anytime. note: don't mix chargers with diffferent types of cells, use the charger that is made for a specific cell.
BatteryJunction sells both chemistries of lithium rechargable batteries, and I believe AW does also. BOth businesses are well respected here.
As far a NiMH rechargables goes, I believe these would be considered very safe, possibly the safest rechargables, although the LiPO4 may approach or equal their safety. The lithiums do deliver more than twice the voltage per cell though, so many lights using them will be brighter.