I think that could be a killer Facebook app (if such a thing doesn't already exist), but I think you're being too smart for your own good. If I want a way to find out if the person I'm into is into me, then I have absolutely no desire not to be warned if there is a match.

I have a similar issue with your chancemail idea. I can just about see the 'let fate decide' value, and also the bit where the receiver gets to pretend it never happened if they wish. But the bit about paying to remove all of this, and add in the receiver's mind the suspicion that you probably did so really muddies the waters.