Everything seems to be working well here in Mavericks. I have no measurements to confirm it, but it feels like there's more overhead, as if I have a 10% faster CPU in big projects. This might be something to do with the compressed memory trick removing virtual memory use. So, it's not like my 2012 MBP is suddenly running like a 12 core new Mac Pro, but it does seem to be a real and noticeable improvement.
A couple of plugins seems to be having trouble running in VEPRO with OSX 10.9 - SWAM plugins from Sample Modeling, and Steven Slate Drums 4 seem to be having trouble, but as a workaround running SWAM plugins in the host software instead of VEP, and switching off Disk Streaming in SSD4 seems to have resolved those problems.
As people say, you need to switch off App Nap for VE PRO.