To take MathPath as an example... Your future 11yo could be learning from John Conway and Robin Hartshorne each summer. You're talking about some of the best research mathemticians in their fields... and getting to hang out with other kids like him. Both of these are HUGE benefits if you can afford it.
Now Epsilon is a similar unique experience... but for our DS7 the value proposition isn't as clear. The social benefits are more muted at a younger age. The faculty is very strong but I feel like we can meet his intellectual needs on our own. Though I am researching geometry texts to go with Euclid in the next year or so. Its a hard call... You could always call or email and get their thoughts. A former director and former professor from Epsilon post on the WTM accelerated boards so you could also look at some old threads there and ask for input.
Good Luck.
ETA. Also my impression is most kids are 9 or 10. Some of the strongest kids may be younger, but either way it sounds like you have some time to figure it out.
The folks who started Epsilon are working on a Delta camp for younger kids (6-7) for next year which could also be an option.
I'm not sure how much a kid with access to two PhD math parents would get out of a math camp. For a kid without such access, mathpath was quite special. I don't know if I would call it life-changing, but it was definitely worth the cost. I do think my child would describe it as the best 4 weeks of life so far -- and just asked, my child would also say it was life-changing.
My sense of these camps is that they aren't for math talented kids, although the kids there are talented in math. They are for kids who LOVE math and who are excited about anything John Conway has to say, who spend free time thinking about mathy things, and who love learning math. I suspect that many kids in the top 0.1% do not fit these criteria and would be disappointed. For the kids who love the math itself, I think these camps can truly amazing.
DS7 absolutely LOVES mathematics, and loves thinking about and talking about mathematics itself purely for its own sake. These camps definitely sound like his thing. When we told him that these camps existed, and that there was
possibility of him going, and he could meet other children like him and do mathematics all day, he was so absolutely thrilled by the prospect that he was overwhelmed with emotion. It definitely has the
potential to be life-changing. (Or it might be a let-down academically and/or socially. And it's expensive. And they might not let him in anyway.) But when DS7 saw it he definitely wanted to go. BTW he'll be 8 next summer (2014), so too old for Delta, and we'd be thinking about summer 2015 anyway.
I definitely see how there is a stronger argument to be made for waiting for MathPath (age 11-14)
www.mathpath.org/rather than Epsilon Camp (age 8-11), though that's a long time for a little kid to wait. The experience (and expense) is postponed, but may be well worth the wait.
