Hi Dottyblue,
I have 2 sons and 1 daughter at SES so can answer most of your questions. I have answered you honestly and from my experience but obviously there are always exceptions.
I don't have children at SJS but have plenty of friends that do and also some that have moved in Y5. Before I responded to this I asked their opinions and they ALL say that their children's transitions have gone very smoothly. The staff and children at SJS have been very helpful and friendly, and as this is a very popular time for new intake the school is very adept at making this as easy as possible.
I have in total 5 boys and 1 girl and have experienced the single sex education system with both sexes, I firmly believe that it works. Boys and girls are totally different, obviously physically, but emotionally too. Girls mature quicker than boys don't they. The structure for the boys is different, the PSHE, the mentor system...their physical but also emotional/mental needs are all catered for. That's not to say they don't mix at all because they do, they mix in school plays, CCF, music - school bands, all kinds of things but up to year 11 they are schooled separately. Sixth form is mixed, they are more mature then to cope with mixed lessons whilst maintaining focus.
Sport - yes Rugby is one of the schools main sport, its tradition which is a good thing but and its a BIG BUT, Rugby is not the only sport on offer and its most certainly not the be all and end all. Boys are encouraged to try all different sports and many are selected to play for school. SS has hundreds of boys taking part in sporting activities on a Saturday at all different levels but this could be hockey, cricket, table tennis, swimming, sailing, shooting, badminton...too many to mention.
The boys are expected to represent their school and their house however this can be in art, maths challenges, drama, music, debating, D/T competitions, science etc etc, they have so many opportunities, all equally as important.
The house system is good for this too, they represent their house either individually or as a whole, from house singing(my favourite) and tug of war to baking. They are great fun and the boys really get involved.
I myself joined SS PTA so I could meet parents, it can be quite lonely if you are parent of a teenager as you don't have the playground socialising like you do during the junior years.
I personally know some members of the SJS P.A and just as SS they are a lovely friendly bunch of people. Its an active P.A and very well supported, they would welcome you with open arms.
I drive an old peugeot and size 10 seems a lifetime ago, trust me it doesn't matter! One of the best things I think that sets the Endowed schools apart from others is the mix of pupils from all different backgrounds. This is why I think the young people who leave, leave as grounded, well rounded and great individuals. I have dropped my children at friends houses, some that have drives a mile long to those where you could barely swing a cat but it doesn't matter, the children don't care. We as parents, whether we have a range rover or a peugeot all have something in common, we simply want to give our children the best possible start we can.
I hope this helps, message me if you would like any further help.
Nikki