I drove through Dorking yesterday, Police in the central reservation over the brow of a hill trying to sneakily catch people out. If they wanted to slow people down because the area was dangerous or had experienced dangerous driving in the past, they'd be before the brow of the hill (to stop people slamming on their brakes), and not bother wasting time trying to collect another tax.
I think the problem with a large proportion of the laser/radar detectors is the lack of understanding of what's common, how they work, and therefore what the deterrents are actually effective against. I'd say most of the cameras on the roads are the static yellow gatso/truvelo/specs ones, so you can cover those with GPS databases, however you dont really want 9 devices in your car, you want one that does everything!
I've always been tempted to buy a Snooper 3zero (as it's the only one that does radar i think..?), but a Pogo lLus would be nice in Europe. Looks much better too, as its so small.