About Terra Nova...Well, the little stereotype about the schools was 'Terra Nova's for old money, Ryleys is for new money'. Being awfully stereotypical now, Ryleys parents run their own businesses or are footballers, Ladybarn parents tend to be doctors and lawyers.
Also I do have some fairly recent experience of Ryleys and LBHS, so hope this will help a little.
My brother was at Ryleys until Year 4 and then transferred to Ladybarn. It was wonderful for him, but he's very competitive, very sporty etc. I think if you were quieter, you may strugggle more, just with the bigger class size.
The reason he moved was that the work at Ryleys just wasn't up to scratch at the time. At the end of Yr 3, some schools do suggest you move less academic children, and unfortunately, in my DBs year, Ryleys took on so many children from other schools that the standard of the class just slipped, as the teachers were more intent on trying to catch the other children up to the required level than continue working with their 'original' pupils.
He moved to Ladybarn, and the tests they did said he was bright, but just hadn't been taught some of the things he needed to know.
I don't want to put you off, just suggest you talk to some of the other parents etc. I know an awful lot left my brother's 'original' year at around the same age. I don't know if that was just an odd year in that they had extra space so filled it iyswim, with unfortunate results.
Probably the best thing to do is see if you can have a trial day at each, and see what your DDs prefer. :)