With subframe connectors in place, what you are creating is a boxed area in the area. The connectors act sort of like an annexed bridge to the factory rocker panel bridge.
As in this crude quick drawing I made below, you can see how the longitude rectangular tube that goes from front to back is also tied in with the transmission crossover tube and a similar sized tube out back just past the rear door jam. This combined with the longitude tube welded to the floor pan also brings more strength to the area.
What I've done is the furthest I would go since it is only oval shaped holes dotted carefully down the bridges topside, so I would not worry about it if you've done the same.