I have used my Momentum wireless 2.0 for a few months now.. short feedback:   I love this headphone! Use it a lot, mostly while watching netflix on my tablet or listening to spotify while mowing the lawn... (I have a lot to mow..noice cancellation is fantastic! Try it in your car!)   Design...

  Easy to test: call your own number and leave a voicemail ;)

Guess you had contact with 'Igor'? He was very helpfull to me (see above). Good service.

  Just installed the BT800. At first had some pairing trouble. Put the headphone in pairing mode first, then the dongle; didn't work. Reversed order worked fine; took a while longer than pairing with eg smartphone though.   Works fantastic now; none of the issues like with the bth-500. Skype...

FYI: Meanwhile received message from Sennheiser NL:   They tested with the BTD800 instead of BTD500. BTD800 worked fine. They now have offered me to replace the 500 with the 800. Good service.

  Have had the same experience. Contacted Sennheiser Netherlands - they support-guy said he tested the BTD500 with the momentum 2.0 and it should work fine... The dongle must be defective, he said, so I had it replaced. Guess what? Same problem.. So the conclusion above seems to be correct...