If your son passes the entrance exam, and if he's prepared to work hard, then it's the place for him.
Every boy there does their work more or less on time - life is difficult there if you don't - mostly because that's what the boys expect from each other.
I don think you actually have to be too much of an independent thinker, tbh racy - no disrepresent to my boy's approach but he is a science graduate and I don't think he really developed his thinking skills until uni. Just listening and learning from the teachers was his approach.
It's not a hothouse I don't think - they only ask what they know is achievable from their boys. Music and sport and drama all matter hugely there too.
So far as recent leavers are concerned, are they happy - were they happy overall? I can only speak for the boys I know from my son's year (left 2009). I don't hear of anyone who was unhappy, or is unhappy now - they're still at the masters stage at uni or have just graduated six months ago so are all doing exciting things in their lives. My sons closest friends are a Group of 6 to 10 boys from RGS and they are all young men to be proud of.
I don't know what else to say, really. If you're not feeling it for RGS, then you're just not feeling it but I don't know of anyone who's ever regretted the decision (also applies to my DDs' boyfriends' years too including current sixth form)