This is quite an old thread so hopefully OP has now looked around several schools, got a better feel for them and she and DS are getting ready to do 11+ exams in the coming weeks. As the chat showed up in active and I have a child at the school I thought I would answer.
Going back to your original questions, OP, the RGS interviews don't try to trip up the children. They are trying to get to know them and get the best out of them. Naturally it can be a little nerve wracking for the boys but the interviewers are kind and considerate. It is a selective school and the bar is fairly high but they don't make the interview an ordeal.
As for pushy - I disagree. The school does have high expectations for the boys and they do work hard. It suits self motivated, academic boys. Contrary to pp's comment about the type of boys they like, my own son is an outgoing, chatty, confident all-rounder. He is bright, hard working, enjoys a broad range of co-curricular activities. His friends are also well balanced all-rounders.
It is a town centre school and doesn't have the luxury of being surrounded by playing fields. That might not appeal to everyone but the facilities they do have are good and the short journeys to offsite facilities are well managed. Hockey, sailing, cross-country, shooting, climbing.... in addition to the sports already mentioned.