OK, I got pretty excited about my new TP & completely forgot about this thread. I haven't had any issues with the 521 & TP. However, the silicone ear hook fell off.
I used some 3M automotive weatherstrip adhesive & it has stayed on so far. That's the only gripe I have with the 521. It's 100 times better than the Motorola HS850 piece of crap I had.