Hmm... I don't think really hear them being all that similar (vs. GR07).
I hear the GR07 as having more upper presence (trending toward sibilance on some things, at least with the MKIIs), probably overall more upper extension, a flatter midbass, thinner more distant mids, perhaps a wider soundstage but with much less depth. Of the mid-tier IEMs I've heard the Shure 535 comes to mind. The GR07 is somewhat leaner and quicker/thinner down low and can be harsh at times, while I'd say the 334 is more of a lush and relaxed listen.
I have a hunch that if you're looking to spend this kind of coin the 1Plus2 probably has more in common, although I'm just going off comparisons I've read between those and the 334s.
Edited by bobeau - 4/14/13 at 9:31pm