In reply to Madwoman - my son is thoroughly enjoying life at MGS - he has just gone into year 8. We live closer to MGS than Oakwood, so logistically it was the first choice. However, he's my eldest child, so it was the first time through the system for us, so we decided to look at both schools with an open mind, and worry about the travel plans later. It was really my son's choice - he is someone who likes boundaries, and likes to know that someone's in charge - and I think he just got that kind of feel about it when we visited. I liked the headteacher's philosophy of 'give me the boy and I will show you the man' - the headmaster has been there a number of years and there is a feeling of stability (possibly famous last words - you never know what's round the corner!) Also, all his friends had chosen MGS as their first choice - so that certainly had some bearing on the decision!
MGS has 'specialist language status', which means the boys have a wide variety of languages (Italian, Spanish, French, German & Latin from year 7, and I believe other languages such as Mandarin later on). I believe Oakwood Park has an 'IT' status, or something (I am sure someone can correct me on that) In reality, how much difference this makes to teaching direction or choices, I'm not too sure.
I have 2 nephews who go to Oakwood, one also in year 8, and one in year 11 - and again, both are thoroughly enjoying school. I think it's a case of going with where your son feels comfortable - academically you can't pass a blade of grass between the schools.
I am just about to go through this hideous process again with my second son - I feel no more confident or more able to deal with the stress than I did first time round. My third son's just started infant school - and who knows what the system will be by then - but I'll be too old/drunk to care by then!!