I will vouch for the Sennheiser headphones any day. I have the little pricey HD-600's, and love them. Just cannot listen to any other headphones after listening to these!
With the good headphones, you are at least assured that you are not missing any frequencies - this should not matter so much with the paraliminals, but with the other products where the frequencies do matter, such as Holosync or Hemi-Sync, it is nice to have that assurance - given, of course, that one's ears are able to receive those frequencies.
Cheers.
