Just bought one here in Hong Kong, very hot on turbo, but that is expected anyway.
Both flat-top and button-top cells can be used.
When the battery is almost empty, the power button starts to flash, is this correct ? I couldn't find any information on this.
Send Klarus an email, they will send you a metal one (via your retailer).
I did and they told me to go back to my retailer to collect a metal one, very good after sales service :)
My very first flashlight was BC10 and it is still one of my favorites. Simple twist head 2 modes, very bright when using 16340, dropped it many times with no problem.