I would just roll with pool filter sand, skip the root tabs. Dosing the water column will provide plants with all necessary nutrients, plus you never have to worry about moving plants and disturbing the root tabs. I'm running into that issue right now, kicking myself for putting them in my tank. Maybe a SLIGHT improvement in certain plants, not enough to justify my inability to trim and replant.
ADA will eventually lose the ability to buffer the water, so I don't think adding less will lower the amount it buffers, it will just shorten the life of the buffering capability because that little bit will be doing more work.