You get what you pay for. I have the A50's (Essentially the wireless version of the 40s) and they are the best headset I've ever used.
Comfort is unmatched - Can be worn for periods of 24+ hours straight with absolutely no discomfort (I've even fallen asleep w/ mine on MANY times)
Sound quality is great, definitely nothing to scoff at
Mic sounds good, very clear.
The wireless is latency free. None. Period. Great for gaming or just standard use
RMA process in the event of a break/failure is painless. Already replaced my headset once due to a crack in the "frame" of the headset.