Thanks for your response!
We'll try to answer all questions:
1. We decided to lower output to 400 lumens. Unlike mbi you can use our light until you drain battery, not only for 15 sec as 'more advanced' mbi hf. We use copper thermal pads for cree xml-l2 u3 and managed a problem with overheating.
2. Mode selector is a button at the end of flashlight. We don't like rotating heads on keychain flashlight.
3. We've created our own driver for that flashlight. To avoid accidental switches modes are changed through double click. Off -> double click -> low -> double click -> med -> double click -> Turbo -> double click -> strobe
But we would like to hear your opinions about the way of switching between different modes. We can program our driver in any way.
4. Heat - extremum will be still comfortable to handle after 5 minutes of turbo mode. Why? Cases are made either from steel or titanium. Both metals haw low thermal conductivity (especially Ti version). Only lens would be rather hot. Bun not to the level to injure somebody.
p.s. Tomorrow we'll start kickstarter campaign and if you're interested please support our project and\or tell about us to your friends. We've already made one successful project
https://www.kickstarter.com/projects/1727819497/cardlight-powerfull-flashlight-in-a-size-of-credit and have only positive feedbacks. Sure, we're not a flashlights guru but we're quickly learning and always trying to keep our promises. No fake lumens, no fake beamshots or lying about runtime.