Alfred143I've been using a 10440 in my copper one for months without issue. It does get hot on high though so you have to watch that. But other than that, zero concerns.
Alfred143The Ti model uses an electrical tail switch, do not use a 10440 in it. There is a small battery in the switch, both my copper and aluminum ones with the regular clicky switch work on 10440. My copper light will now only work with them actually. Been reported on some of the forums that you may burn up something on the PCB with the higher voltage and alkaline will no longer turn the light on.