I've tried Cree Led bulbs for my brake lights and they are great.
I have a light meter and did some tests to prove it wasn't just a placebo effect.
A 5W Cree brake light, gives off significantly more brightness than the original 21W incandescent bulbs.
Incidentally, I've changed my front side lights, and rear tail lights, brake lights, and number plate lights all to LED's. This is to reduce the drag to the alternator, that causes the idle speed to drop when you put the lights on. I was finding myself winding up the idle speed on the carb to compensate, and then the next day you'd drive without lights and the idle would be too high and 1st gear would crunch! Led bulbs solve this problem.
I haven't changed the indicators because I think the lower wattage would affect their "blink" rate, and I haven't done the headlights because I don't think there is an led replacement for those old 410 globes.