I think a lot of it depends on the type of mbuna you keep. The species I keep don't really become tankbusters (L. caeruleus, Ps. demasoni, Ps. elongatus, L. fuelleborni) and haven't really been a problem. Only the Labs show any real propensity for digging, and I give them an area behind some of the hardscape and out of view that I call 'the sandbox' for them to dig in. They seem perfectly happy to dig there. I did have some issues with my Glosso and some of the smaller plants until they got rooted. Believe me, I was replanting about 50% of the Glosso every morning until the root system got established, but I decided I was going to be more stubborn than the fish and, in the end, it worked out. I've found that once a plant gets its root system anchored into the substrate the mbuna will leave it alone as it's just too much effort for them to pull it up. I think it is probably best to keep only young mbuna in a newly started planted tank as they will have less impact on the plants until the plants can get established. Plus I think growing up around all of the plants, the fish get used to the idea of them being there and aren't as resistant to the idea as if the plants had been introduced after the fact.