Both my girls fight furiosly. One is 2.8lbs and the other one is close to 7lbs. I do have to watch them closely but otherwise they love to play fight. There dogs
. When they play with you do they bite down hard? if so teach them not to. If they don't bite then it should be ok for them to play. Some train them not to bite at all I just train mine not to bite down.
There like kids they will get on your nerves. Good luck with whatever you decide.