A street-level team title

[married guy]

I could get behind the idea of a street level team depending on the creative team and line up. However, the OP's idea probably only works as a quasi-team up book. The core of the title could be Batman, Green Arrow, and Black Lightning...or Green Arrow, Blue Beetle, and Batwoman...or whoever. Then every couple of issues guest stars rotate in and out of the arc.

So the three main heroes take on a case and during the arc they meet up with two or three other heroes. That way depending on the story, you can include anyone from the Creeper, to Wildcat, to Manhunter.

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