As the demand for higher BEC voltage ”drives” the RC Community, I know for myself when I purchased my first full set of 7.4volt servos for a helicopter I wanted a 7.4v BEC. As Igor says, one can solve this the ”ugly” way with diodes, OR incorporate an LM7805 regulator and two capacitors in addition to the current timer circuit design. As I build my timers on rasterboard, they are already kinda large. If I where to incorporate a regulator I think I have to start making a real PCB for my timer. Another way would be, as William says, to use a separate 5v BEC from the battery (in my case a 4s) to the timer and disconnect the positive wire from the ESC. I have read about the KR timers and he states an absolute maximum of 6v, but preferes 5-5.5v BEC voltage. I found a manual for a Hubin timer online the other day, and I could swear he say not above 5v, but I could not find it now so I`m not absolutely sure.
Sooner or later ESC BEC voltage will be 6v+ and current timer designs need to be adopted to that. I use Picaxe microcontrollers for my timers and the chip design states a vcc voltage of 3.3-5vdc.
Igor: Hypotetically, if I where to send you this ”super-duper-über-F2B” ESC with a 7.4v BEC, what would you do?