I wouldn't expect a big premium if VRUS were taken over at this point (for that matter nor for ITMN). Just a guess but I would say in the ~20% range. For what its worth I think it would be a bit of risk still for someone to take over VRUS.
There are so many ways VRUS can leverage their assets and remain the leader in the space. I can assure you a 20% premium would not only be unacceptable to management and shareholders, but it would draw in competing bid(s), at much higher prices. I think it would be a bit of a risk not to pay top dollar and put the company into play.