theta I know the demographics of the school pretty well and would never give misinformation. The problem overwhelmingly is that too much other misinformation abounds and puts strong local applicants off (too posh, too pushy, full of over-tutored downshifters etc.).
No Exeter parents will be put off by someone saying (correctly) that kids from Exeter to the west and Bridport to the east are the exception not the rule. Or rather, that the vast majority of kids come from a more central area around the school. Even your numbers divided by seven show that's correct. So hardly 'misinformation'!
If Exeter parents are likely to be put off at all then it's by the hour their kids will have to spend on the bus at the start and end of each day (though plenty don't mind it and some even like it I know) and the requirement for a 40 mile round trip to collect after matches, concerts etc. That's if they can afford the fares, which are steep and a major concern for some. Geographically OP sounds much better placed!
As for admissions, I wouldn't have a clue which of my kids' friends scored L5 in Y5; do mums really compare and do kids themselves even know? Scary...! I don't think mine were all L5 in Y5 but they're doing ok (perhaps I should reserve judgment on that until after results day in Aug!).
What I do know is that the 11+ has evolved in the past few years and the current rule is that a child has to pass the English paper and then has to be in the top 120 when the Verbal Reasoning and Maths are combined, also that the old Borderzone has gone.
The OP is really asking about Woodroffe anyhow. There were some Woodroffe MNers around, I saw one current one on the thread which got deleted. She might be able to help OP more on how a bright, quiet DS would fare at Woodroffe. I know quite a few with kids there and would have been a bit worried about my eldest and youngest DS, much less about the more football crazy boistrous DS.