From a driver's perspective (and I'll admit I'm only an occasional one, especially in the dark) I've always found flashing front lights freak me out, because the intermittent light makes it impossible to place the cyclist in one's field of view. Perhaps it's because of how bright lights are these days, but they confuse and dazzle far more than static ones (and, indeed, flashing rear red ones that seem to be OK), so I'd never use them myself.
mmm, interesting comment.
personally i find that a flashing front light on a bike makes it very visible even in the day time. very similar to the way motorcyclist keep their headlights on during the day. in fact you can't actually turn the headlight off on my motorbike