Nothing wrong with that, but I don't find it necessary. If I'm working something heavy, I shift some gas to compensate.
If I was shooting a rig that was negative on a regular basis, I'd make it slightly positive. That would provide the added benefit of the camera floating to the surface if it were lost, which would make it easier to find. Why dive with a brick?
Shifting gas works when you stay in perfect trim. However, I sometimes have to break trim to get the shot and ankle weights make it so simple.
As for the camera, it's hardly a brick but it is about 2lb negative. I like it that way as the weight helps to keep it steady.