cd-card-biz,
...Until very recently the conventional wisdom was that primary 123 cells are safer than rechargeable Lithium ions. The recent mishaps with primary cells seem to have changed the thinking. However, I do not think we have enough information to accurately say which is safer. There are many many times more primary cells in use than rechareables and mishaps with them are actually not too common. I have had a thread running on the batteries and other electronics section for quite awhile asking for reports of mishaps with unprotected rechargeable lithium ion cells. So far no reports (except for some intentionally abusive testing) but I do not think that there is enough evidence to say for sure that rechargeables are safer. I do think we should be careful with all of these cells. They pack a lot of energy into a small package. I would base my decision on which cells to run in the new Pila GL4 550 light on economics rather than my perceived (sp?) idea about which is safer. Either way you go that light sucks a lot of electrons and should be used for short bursts so that it and the cells do not get too hot. Accidentally leave it on unattended with either type cell and things are probably gonna get hot to the point of damaging something.
Be careful out there,
jc