The thing about aid another is its not the bonus that makes it so strong, its the fact that a person with a low skill can take themselves out of the skill challenge.
At the most powerful, a team of 5 with one guy having a very high skill, every other player "drops out" effectively and the one guy makes all the rolls. This actually has a tremendous impact on a party's win rate. Even with only letting 3 people aid, you still have that huge effect.
Fart, I knew you'd say that

and it's as I thought. But this leads me to another question about your Skill Challenge systems. How do they handle "
AGAINST THE CLOCK" challenges.
That is to say if the challenge has a time limit. Not real world time but game time, say in 3 rounds a party of 4 must acheive 7 sucesses before 5 failures. So in this scenario it would make sense (time wise) for each party member to roll for a success each round to try and reach the goal before time runs out, (
and the Temple guards come round the corner)
In the above scenario, they could though use the "Aid Another" option but at there own peril. As sure it will increase the likelyhood of sucesses vs. failures, but also they are drastically reducing the chance at multiple sucesses in the time they have.
I'm guessing the entire Time thing is Abstracted in the first place so this might all be moot. And I totally understand the cause and effect by removing a party members from the rolls and how this effects the PWR, but it just rubs me wrong that more than one can't Aid Another. Or the idea some people seem to have that Aid Another may not even be allowed at all in Skill Challenges.
IMO Aid Another should be allowed (within reason, even if it's an arbitrary limit) but there should also be consequences for to many Party Members not making there own rolls as well. I'm sure you've Grok'd this all before Stalker0. It just seems natural and intuitive to me some party members would be allowed to assist another in a sense.
One More Question though.
If I was to allow up to a max of 3 party members to "Aid Another" with each garnering a max of +1 to the aid (and an overall max of +3) the +3 part of the bonus doesn't throw the equation out of whack right. It's the fact that now 3 not just 1 are not rolling that throws off the math. I guess in a vs. Time & Successes scenario as opposed to a vs. Successes scenario I don't mind the math being thrown off a bit, cause there are consequences for said choice.