I used to have ER-6i set but then the left earpiece went silent. Now I use a set of Sennheiser CX500. The sound quality was probably tad better with ERs as CX500 seem to have bit heavy on the bass - of course this depends what kind of music one listens. CXs have also volume adjustment on the cable which is nice.
My major gripe with ERs is that quite deep in to the ear, and therefore are bit irritating for long use and also they tend "extract" ear wax so that the ear piece has to cleaned often. Additionally, when I used them in the office and peole were asking something from me, it came quite a chore to take them out and put them back in. CXs isolate quite well (used with smile on airplane) + they are easy put and take away.
im using Sennheiser MM 200's. Excellent sound quality, first set of bluetooth ear buds that I am able to control the music with from the headset. There is a slight hissing but its not too bad. Not the best choice for avid joggers, every hit on the wires sounds like a stethoscope so what I do is place the wires and set on my hat. Overall I would def recommend these.
i've been using the ones that came with the phone but one of the buds have gone missing.
i think the sound is decent for a set that came with a device.
was contemplating buying the nokia wh-701 headset to replace them as the have a remote which is something i'd like....if it will work with the n900.
does anybody know if it's compatible or know of any good in-ear canal earphones with a remote (not fussed about a mic) that will work perfectly with the n900?
love em 
sony mdrex75