That's true. My buddy has 8 saulosi in his 30g (2M/6F) and they seem to be just fine. From what I've noticed, they don't seem as aggressive as other mbuna can be. But they have only been in there about six months, so they aren't all that big. He says he's gonna get them a 75g this summer though (since I keep on him about it being so small).
Since LuvMyKribs has corrected my assumption on the size of saulosi, I would only suggest the POSSIBLITY of a demasoni species tank. But beware.....these may be smaller mbuna, but they can be very nasty for their size. Especially toward their own kind!
Again, look into Tanganyika. They really offer many more solutions for a 30g. In the end, you're probably going to end up with alot of casualties trying to keep mbuna in a 30g. The price of losing many fish would probably pay for a larger tank.