No, it's probably worse.
The Beyer DT880 completelly destroys the GMP 400 here so I would think that's the case with the Sennies.
The "Cardamatic" GMPs still employ dated materials in construction.
SQ wise I can't comment about the Sennies...
Here's a comparison with the HD650 - http://reproductormp3.net/index.php?topic=15641.0