This will also save you all the agonising over the 11+ and any recriminations later from your daughter.
Recriminations later can also include 'you should have made me do it'. I've seen it before.
Remember you are the adult and best suited to make decisions for your child. Yes you want a happy child but its your reponsibility to make the correct decision on her behalf even if done in a sneaky parent kind of way. I have just negotiated this quite sucessfully although it helped that we looked at the grammars a year early which gave me plenty of time to work on my sales pitch.
Whatever you decide remember nobody knows your daughter like you do and only you can make what you hope is the best decision.
It really is very stressful for us parents although I'm sure its a good time of year for the makers of biscuits and all things bad for the waist line - oh the comfort eating!!!!
Good luck whatever you decide to do