Access have stated that they are aware of an issue with older Virus TI boards not functioning properly in the OS Mavericks. I have used the TI for about 8 years. Here's what I know:
I use Ableton 9. Presonus Studio live 24.4.2AI. Late 2013 MBP
You can use your TI as a USB controller to your peripheral devices. This will only work as long as VC is NOT open.
You can use VC to control the virus TI, with a separate USB controller keyboard. For example: I can use a korg micro key to use the virus TI via virus control with LESS problems. Still a little latency some false starts and stops (as usual).
You can use The Virus in midi mode (the old way) with no issues what so ever, however use lose functionality of VC.
You cannot use the virus TI keyboard itself for anything while VC is loaded.
The Virus TI will NOT control peripheral devices while VC is active.
There is a Root Hub issue whether using a physical USB hub or not.
The root hub issue is NOT caused by your MAC. None of my other devices have issues. I am running 6 peripherals on one StarTech hub.
There is no latency on my other peripheral devices in the USB hub. The virus TI at max runs 17mbit data. This is negligible in the USB 3.0 environment.
The issue is with VC.
Fix it. I didn't pay 2000.00 dollars for a keyboard that stops working. OR. Authorize a repair on my board.