I haven't heard the VR-33s, but I have VR-4s and have also had Zu speakers. The two brands differ a good deal in their presentation. I wouldn't call Zus bright, but I would say that they are more forward than my Von Schweikerts, which are a bit more laid back. So this could be a matter of which sort of presentation you prefer. For some a more forward spaeker can get fatiguing. For others, the less in-your-face nature of a laid back speaker may not appeal.
I would say that if you get Zus you would probably benefit from getting a lower power amp at some point. Tubes (SETs, Push-pull and OTL) with Zus sound very nice. Or in the solid-state realm, I'd look at the FirstWatt amps designed by Nelson Pass. Gopher has done extensive amp combos with both Von Schweikerts and the Zus, so would be an excellent resource for either one, but be sure you know how your tastes line up with the tastes of another. For example, I bought an OTL Atma-sphere S-30 from Gopher. Too lean for his tastes with his Zu Superflys. I loved the pairing with my Superflys, really digging the speed and immediacy. Gopher wanted a bit more meat on the bones and went to an 845 SET amp, IIRC.
And I have moved from the high-efficiency world to the Von Schwiekerts, which I really love. Fabulous imaging and detail. Mine go down to 20Hz, which is good for a bass head like me. That said, they are a touch too laid back at times for me, and to get a more forward sound I have focused on making choices upstream that will tp the speakers a bit more in that direction (Rogue Stereo 90 tube amp for example. IIRC, Gopher also quite liked a Rogue with the VR-33s).
Hope all this helps. These are fairly different speakers, so if at all possible I'd try to hear both. If you can't do that, be sure you have a clear idea of your listening preferences, and what you are most looking for in a speaker. Both speaker makers have big fans, as well as folks for aren't big fans.