I think the problem with accelerating children who are several years ahead is that you'd have to accelerate them several years to make it worthwhile. And to my mind, that would be a disaster socially - you would be robbing them of their childhood.
If we had gone along with the school's suggestion to put dd up a year, she'd still have needed differentiated work, so not really sure what we would have achieved. And putting her up by any more than a year would have been cruel from a social point of view - she is physically quite small and slight in any case, and I think she would have been viewed as some sort of freak. Who would want that for their child?
As it is, she is blissfully happy with her peer group. Her friends all seem to acknowledge that she is "clever" but it is no big deal. She gets her own work in class when they're doing maths and she has her own targets for literacy etc. She is able to work alongside her classmates for art, pe, ict etc.
I would really, really think long and hard about what you want to achieve by acceleration before going through with this. If 1 academic year would be enough to bring her in line academically, then she is not actually that far ahead, and the teacher should easily be able to cater for her in class without the need to disrupt her friendships. If 1 academic year isn't enough to bring her in line academically, then accelerating her by a year seems pointless as it won't solve the problem anyway - and you have to ask yourself how far up the school you would be willing to push her, to get her in the "right" place.
You may find things are different in year 1 anyway. Reception is all about child-led activity and learning through play, so to some extent, it's up to the bright kids to stretch themselves! We found year 1 quite different in terms of the teacher actively challenging dd and setting her individual targets.