The biggest issue I've found with angels and especially super angels is that their fingers are in so many pies, that very often they're already fingering the same (or a very similar) type of pie that you're offering. You'd want to know exactly what they have a stake in before making an approach, yet often that information is hard to find (or purposely concealed.) Overlapping feature sets. Conflicts of interest. Picki…
In my experience, investors are pretty up-front about potential conflicts, and anything you'd possibly share with them isn't going to hurt your business. If you want to raise money, paranoia about angels isn't the way to go about it.
Open question: which investors have websites, as linked from their twitter accounts, that display all their investments?
Does Y Combinator?