i agree, that if there was a single person to provide feedback to, i would. but compare that with a fairly consistent stream of "hey, help this person out" emails, and I think you'd come to the same eventual conclusion...
curious - how many different people have sent you favor requests?
I get about 10 intros a week. 80% come from the top 2 people, David Crow at OMERS and Zak Homuth from Upverter (a YC company). I consistently meet amazing people. There were a couple people that used to intro me, but I've asked them to stop politely.
maybe i'm missing something here - are you the one looking to meet people, or are you already full-time working? if its the former, then of course you want all the intro's you can take! let's agree that if you are out looking to meet people, then you most certainly want every intro possible - but my take on it is if you want the most effective intro's, they are double opt-in...