How old is your dc? Symonds has about 40 boarding places pa I think. It is competitive to get in, and if you look at the website it has a sort of pecking order for boarders; Forces, Falklands, Crown Servants (FCO/MOD civil servant overseas).
I applied as early as I could, (so July last year), and went back to UK to deliver the form. Ds had interview in October, and we were told it would be December, but we heard in November that he was in as a boarder, and he goes in September. I am really envious.
I also went to PSC almost 30 years ago and had the best time. One of the other Mums at ds's current school was a year ahead of me, and we both say we'd go back tomorrow like a shot as it was such a great place (she didn't board, I did).
Having attended one of the the open evenings last year for PSC, I was impressed by the wide range of subjects they do at A level; and there is no intention to offer IB there. A level vs IB depends on your child - my ds could do it, but wants to do all humanities A levels (much to my surprise).
We chose PSC because I knew about it, but also because academically it is excellent; has dedicated A level teaching; and is easy to get to from where we are abroad. We also have family in Hampshire and his godmother is a housemistress at a private school fairly nearby, so he has a support system around him. As a sixth form, it will provide him with a stepping stone between living at home, and going to uni. He will have to learn to manage money, do his own washing, and organise himself, but with the support of the houseparents, so an adult is always there if they screw up.