I think that capacitors adding a ~1-2% vent speed is a pretty good idea. (For me, at least
)
My tactics usually involve getting in, taking small hits, getting out and venting in a flash. When I decide to add capacitors, it takes more time to vent (less vents + higher capacity), which makes my attack runs take longer to complete. If the capacitors added a slight vent bonus (it doesn't even have to be 1%) I might consider using them more often. However, if I get a capital ship, knowing me, I'll max out the capacitors for a high capacity and high vent bonus.
A way to stop this problem is to cap the vent bonus from capacitors at a certain percentage. Something like 1%/2%/4%/8% or similar. This would increase the capacity and venting speed for each capacitor, while also keeping the capacitors balanced.
Just a thought.