I just tried the Flat top Windyfire’s I have , they work fine and it takes a heck of a jolt straight back to get a blink out of the light. The Efest and AWT High drain button tops wont loose contact at all and of course the protected cell that came with it is even a little longer.

EDIT: I can see where it could be a problem if you use a cell that is not raised at all on top (the windyfire is very slightly raised) but the driver end is really flat where the cell makes contact so yea a button top may be best for safety really.