2) They are unusual in the Devon/Somerset area so should be noticed to some extent
Yeah, they were unusual on Audaxes too until Greenbank started this thread [insert ironic grumpy smiley here]
It's true that they do lose some of their reflective qualities with road grime, but I find a quick soak, wipe and rinse in some muckoff every now and then keeps them reflective enough. I've had mine on my wheels constantly for about a year now, and they still reflect.
They're easy to clip on and off, and I've never had even hint that they might come off of their own accord.
Can I have 72 please Alex (Mrs jwo would like some for her bike).