That's a pretty solid idea!
Like Morrison's take on the JLA - a rotating chair(s) when specialists are required.
I also like the idea of a covert super-hero group running missions alongside & against people like Checkmate and ARGUS etc.
A covert group who actually DO get things done on the down low without the Big Guns or the collateral damage.
Got an alien invasion? Call the JLA. Got a dodgy Middle Eastern terrorist cell looking to purchase 'dirty' metahuman suicide bombers? Call these guys