I've also been using the 3.3/3.4 beta for some months now, and I'm quite impressed with the (substantial) improvements over the prior (1.8/1.9) version of VrayForC4D. VrayForC4D is (finally) getting very, very close to full parity with ChaosGroup's "main" Vray implementations on Max and Maya, and the general pace of VrayForC4D development has improved substantially. The LAUBlab team have migrated VrayForC4D to the latest Vray core from ChaosGroup, and on top of all the other feature benefits, doing so means VrayForC4D now has viable interoperability with other Vray implementations.
I find the new version of Vray (CPU) to be generally faster, more flexible, and substantially easier to "tune" and configure. The denoiser is a welcome addition, and can substantially reduce overall render time requirements. The VrayRT (GPU) engine, though still limited in certain ways, is about as capable on C4D as either Max or Maya for the most part. If your scene fits within the limitations, the performance benefits VrayRT provides are nearly worth the price of the upgrade by itself. The complete list of added and improved features in VrayForC4D is quite lengthy (see here).
I'm very satisfied with all the work the LAUBlab folks have put into VrayForC4D, it has definitely paid off for them in VrayForC4D 3.4. I upgraded as soon as I could based on my beta experiences, and am very glad I did so.