I have both of these and they truly sound great both of them. I do however favor the P7 for two reasons: 1. it fits over my ears (the Momentums doesn't exactly hurt my ears but it doesn't feel good either). 2. the P7 is a little bit more engaging and seals better giving it better bass.
I'm fairly certain the shape of my head is the biggest difference between them.
Edited by sparkofinsanity - 5/6/15 at 9:32am