Can Shapeshifters take more than one form or are they limited to a single form?

Remember that Shapeshifters aren't people who turn into animals, but animals who turn into people. That, in itself, may answer your question.

i allow shapeshifters to take as many different human forms as they want but their stats do not change.

That's too powerful as the Shapeshifter now becomes the ultimate infiltrator/assassin. Hit the target, change into his/her animal shape, run, and then change back into a DIFFERENT human shape... too powerful.

ive had no problems with balance with shapeshifters, baroques, or anything else. especially seeing as anyone with astral perception can recognize the shifter.

what may be broken to some works fine for others. ive had no problems with any of the third edition rules.