Have only just logged on again after the Xmas break and was surprised that nobody has responded to your posting.
I have only ever had one bitch spayed and must say that it has had an effect on her behaviour as well as her coat!! She is definitely noisier since she has been done.
I do know that there has been some research done on the effects of spaying and castration, will try and find some reference to it but I have recently moved house and everything is in a state of disarray!!
Will be interested to know what the vet has to say about her behaviour! I think that vets should give more information about the possible side effects of the op.