It depends what you want out of the tank. A breeders purpose is to house fish as economically as possible in order to maximize the profit. The sub-par conditions they keep them in are acceptable because it's on a short term basis and the fish won't be growing much bigger before they're sold. I'll bet waterchanges are done almost daily too. You can do this tank, but I don't quite see the draw of a home aquarium that looks like a fish store tank.
If was considering a 29 I would choose 10 juveniles with the longer term goal of 8 (of any ratio as long as females are predominant). While I was there I'd pick up a 3 foot tank for them (at least).
There just isn't room in a two foot tank for the rocks it takes to house 6 or 8 labs along with space for the fish. rockscaping is vital so the fish to explore and hide as they want. An empty tank full of fish is a pretty boring tank. reminiscent of... a fish store. Give them a playground and some space and you'll start to see how they really are. There is nothing wrong with the 29, but these aren't the fish they're meant for.
