Sorry IO540, subjective opinion on the Bose X as I've recently bought a set and am not impressed. After reading all the hype I was expecting more, like maybe a bit of high frequency attenuation. I remain to be convinced but I find it hard to see how the price can be justified - £400 maybe but £750 is just taking the piss. If they don't start impressing soon they will be on ebay in a couple of weeks.
My DC10-30s on the other hand have never failed to satisfy (once I'd found out how to turn the mic gain down) although on reflection I would prefer an electret mic as my major irritation is hiss rather than boom, as it were.
Telex Echelons are too flimsy for club use, epecially the thin plastic on the foam ear seals which tears very quickly. Also the rotating plastic blocks on the earpieces used to vary the clamping force can dig into your head......VERY VERY VERY annoying.