My daughter sat this exam this year and was given a place. She only sat from Bromley High and Wally Hall. I understand that the test was challenging but have no idea how it compares to other schools. The interview was very relaxed for her and having met the Headmistress I would say she knows exactly what she is looking for. I live around 40 minutes drive away but have chosen Wally Hall because it ticks all my boxes. My daughter went there yesterday for an induction and came out absolutely beaming. Although I haven't any experience of the school, I have no doubt that I have made the right choice. The sixth formers I met were very confident yet pleasant and all striving for academic excellence. The drama and music dept have an excellent reputation and they seem to have some fantastic teachers on board. At the end of the day, it's down to personal choice and what you feel is the right school for your daughter.
Out of the 3 girls independents locally (Coombe Bank, Kent College and Wally Hall) the Wally Hall girls are reputed to be the brainiest. No idea if its actually true though. I know dc that have been to KC and CB but none from WH I'm afraid.