I personally wouldn't keep any puffer with BBG's, but a lot of people seem to have done it without problems.
There are plants in one of my brackish tanks right now that seem to be doing well. At ~1.006, Vallisneria, Java moss, and microsword are growing without problems. Even the little bit of Glossostigma I put in there seems to be hanging on. The SG used to be higher, and at that time, frogbit and red tiger lotus died in the tank.
I'm waiting till I have more plants to spare before I try other species.