erm...schools..tough one. Still a long way also...we can't even plan for weekends, much less plan for primary school! LOL!
This whole primary school talk requires some detailed social analysis. I can only speak from my experience and exposure.
FOr me, my path is IJ-MGS-CJC-NTU. My hubby was from neighbourhood pri & sec (i also dunno what!! LOL!) then CJC-NUS.
I think we are different in terms of our lifestyle and hobbies cuz of friends, as well as family grooming.
FAMILIES:
For me, my parents are huge advocates of multi-faceted life. My bro and I were encoruaged to join ECAs, have friends, given freedom to go out as we pleased. We also started earning tuition money from secondary school. My bro always did VERY WELL in school...while i'm the one struggling to keep up. (He got the As, i got the Cs and Ds.

) We both got to learn many things - Art, Piano etc (violin, basketball, soccer, table tennis, tennis for him, ballet, martial arts, netball for me, etc)
I think the most diverse part of life came in Uni and post-uni days.
I had 2 diverse groups of friends. One was damn super rojak - ppl from all walks of life with diff education background and levels; one was spent with this bunch of 'elites'. (that's what i call them cuz half the cohort are scholars.)
For the rojak gang, i find that yuo have to be a person who really knows yourself to stand your ground and your beliefs since there is no commonality except we love to 'chiong'. hah.
For the 'elites', it can be pressurizing but i see a few things that are nice.
Contrary to common misconception, we eat at hawker centres more than some other groups of friends we have, especially after our weekly netball sessions (guys + girls).
We spend a lot of time just sitting around talking for hours - which is very very interesting and engaging. No need for secondary activities. Of course also got chiong and play pool and other stuff.
THey are very receptive of people - no matter what background etc and will talk to anyone about anything. I think it comes with having a wider knowledge base and perspective on life.
"failure rate"? So far, i only know of one who couldn't take the pressure of the RI-HPark cohort in secondary school and got sent abroad to study. I heard he 'cracked' under the pressure to perform or what. Not sure. THe rest are mostly lawyers/docs/etc.
Their thought process and perspectives are also quite different. When presented with a problem, the focus is on problem-solving and not worrying and etc. They seem to be very objective and able to detach themselves from the situation to see a bigger picture.
Profile wise, I think 80% are from rather well-to-do families while the remaining are from 'normal' middle-class families.
I'm sorry i have no great conclusion. But i agree with the general notion that it's the FAMILy that grounds a person. The school/social atmosphere can make or break thatperson, depending on many other dynamics. That may really be a common ground for all these people - that their parents nurture and provide an encouraging atmosphere to learning?
I think I'm abit traumatized by my mum's nag-nag-nag-till-it's-perfect and i-told-u-so upbringing. I'm grateful at how dedicated she is. And while she gave us a lot of space to grow, she also slammed you when you failed and could say very very condescending things...something which i see in myself at times when i get very angry. Lucky i can still 'sense' it and know i am quite unreasonable (despite it being very hard to control!!!) But that's family. No one's perfect. The good and the bad come together. What's important is that my parents were with me all the way...never giving up.
My hubby is a teacher in JC and sometimes i tell him off - that worrying is for the parents, not the teachers!! Tell him to worry for his own girl instead of his students - whom he have no control over. They dun study is not teacher's business/perrogative!
Friends are also very impt. I mixed with "good" and "bad" groups before and even repeated my first year in JC. Between "good and bad", also got their own types. The first i met, play and dun study.
But the second batch, though even more 'ah beng' and 'ah lian', they will study very hard, and then play like siao.
It was through these 2 batches of friends that i saw how you can be 'hardworking' and 'cool' at the same time in school, instead of just hardworking (geek) or just cool (failure!!!).
heh. paiseh if irrelevant. but just flashing out case studies for reference! Heh!