I've got a pair of Sennheiser cordless headphones too and the sound quality is excellent, not too heavy and very comfortable on the ears even after long periods. The ears don't get hot and sweaty. The pads unclip very easly for cleaning but they do stay on well when refitted
They last many hours on a charge although as they use rechargeable aaa batteries you can very easly pop a normal pair of batteries in if you get caught out
The only down sides are if the headphones are sat on the charging stand correctly then I can loose proper contact with the recharging so I sit them a bit further in front when on the stand.
The other problem is the hinges creaked badly although I found moisturiser to be the best cure!
and the only minor thing is it's easy to accidentaly nudge the tuning wheel so losing contact with the base station until you give an adjustment to retune.
The down bits aside I'm very happy with them
There the second ones listed from the bottom on this link
http://www.maplin.co.uk/Search.aspx?menuno=13228&FromMenu=y&doy=14m7&MenuName=Sennheiser