I understand what all the hoopla is about here but many times I think the absence of rounds being fired at CV is the fact that it is not in view of the SB. I have many times sat in the SB knowing that in 5-10 minutes it will be inside the view and will stay in the SB while I go to the bathroom and get a fresh beer from the frig.
To that I have now that maybe 1% of the time it is a spy and the icon might help with that but then the guy that is trying to learn and not hitting the CV or having trouble getting range is likely to be barrated for it.
As for the booting out of it for not firing a shot in 5 minutes, I could live with it but again I don't think it will solve anything. The person will simply fire the gun any where but the CV every 4 mintues.
I personally haven't witnessed many times that a cv was within reach of a SB and not had someone in there firing it, of course I may not be paying close enough attention to it either.