...In my unscientific view it is better to stop the noise reaching the ears (Etymotics approach) rather than add out-of-phase noise on top of the noise (Bose et al approach), isn't it?
Agree completely, but it's hard to compare them, because Bose is an over the ear headphone and Etymotic goes in the ear canal (all the way in), so both have benefits/disadvantages the other does not have. I own Bose, but I'm going to buy Etymotic as well, because neither is perfect for all situations.