My eldest daughter went to a super-selective grammar. She was tutored for the maths element of the 11+, although not hot-housed as she was very able anyway (primary school simply did not teach maths to the required level).
She loved it, and it was right for her. However, we did come across some students who had been hot-housed for the 11+, and whilst a number of them were OK, there were others who struggled and would perhaps have been happier in the top sets of a good comprehensive.
One other drawback for us was that the grammar she went to (and it was the nearest one) was almost 20 miles away. It meant leaving home just after 7.00am and getting back between 5.00 and 6.00pm, so a very long day, with homework on top. 7 years of that took their toll. She tended to get very tired and was ill much more often than her younger sisters.
We chose grammar for her in part because of her ability and in part because our local comprehensive had been struggling for a few years. It had just appointed a new headteacher (I am talking back in 2006-ish, when my daughter was transferring to secondary school). Seven years on now, and our local comprehensive has been turned around. It is very much on the up. Our two younger girls have not gone the grammar school route. It would not have been suitable for my middle daughter anyway (more practical than academic). My youngest could probably have done well at the 11+, but since we were now happy with the local school she has gone there. She is in top sets and very happy.
My children are a case in point for those who point out that whilst grammar suits some children, it does not suit others. There are many, many factors to take into account. Visit all potential schools with your daughter, including the grammar. See what you both feel then. I too think that you really already know what your gut feeling is, and there is something to be said for a shorter schoolday, locally and with good local friends. It isn't all about academia. It is also about balance, which I don't think we had enough of with my eldest daughter.