The JVC sz2000 isn't, in my opinion, a "basshead" headphone. It has great bass, but it just plays with authority rather than the typical bloated BOOM-BOOM-BOOM bass you get in sony's xb-series or the v-moda m-100. If it's just bass quantity you're after, you're better off with the m-100. If you value sound quality, listen to a wide variety of music and want something that plays it with warmth and authority - you should take a look at the sz2000.
Personally I'm happy the JVC isn't another one trick bass pony. I enjoy my m100 when I'm in a party sort of mood and just want to play loud with some trance/dubstep/rap, but for everything else I rather put on the sz2000.