I have two boys at Frensham Heights.
We love it but then you will always get that perspective from parents who choose it!
It is like Bedales, but less posh. I found the parents at their 'nice' state junior & primary schools more of a pain. No uniform but most kids dress sensibly, no labels and fashion items. PE kit is the only thing that is banded.
I have two very different boys - one struggles socially but is very bright. He has been given the space to be himself and solitude, which he likes. He complains that some of the kids are not as smart as him. There is a wide range of abilities, from children with dyslexia to kids at the top end. They stream from yr 9 I think.
I would say the teaching is generally of a good standard, they don't have problems recruiting teachers. In year 9 your son will get a lesson a week in dance, drama, music, art, CDT and 3D design. Great for confidence and creativity.
My other son is social and active, he loves all the space to explore. He lacks a bit of academic confidence but is starting to believe in himself.
Eldest was bullied a little, but school dealt with it and has not returned.
The boarders are a minority I think, there doesn't seem to be any divisions between the boarders and day kids.
Because it is not an academic hothouse the parents mostly live quite locally, Farnham, Godalming, Elstead, few in Guildford. Few overseas boarders, but not dominated by one nationality.
They do a great Open Day, mostly are full but both mine joined mid-term after spaces came up.
As you can see I am a convert!