Noise-cancelling ear-phones: any good? Do you use them? If so, which ones? I've glanced at the Sony MDRNC11 (I like Sony), Philips SHN2500 and JVC HA-NCX77. Better than the plain ordinary isolating ones (Sennheiser CX) which just keep the outside noise out and the inside noise in? I'll be using them on the bike. Possibly.