I really don't like this idea. It feels…bad. And here's the part where I explain!
First off, it would feel redundant. I have a feeling that any 'angel fruit' powers that anybody could think up could be done with the devil fruit. Seriously. It could probably be covered under either the Zoan, Paramecia, or Logia types of Devil Fruit. The guidelines for paramecia are vague enough to accomodate anything that isn't Logia or Zoan.
Secondly, this sounds like an excuse to get rid of the "Oh noes I can't swim" downside. Even if you stuck another downside on there, it would not feel right. In One Piece, not being able to swim is a serious threat to one's well-being, what with the fact that the OP world is most likely more than 50% water.
Next up, the concept of the 'angel fruits' is obviously a direct opposite to the devil fruits. Oda doesn't really do that. There aren't opposites to the giants, are there? As for the fishmen and the mermen, I think that they aren't really opposites. They're just similar.
Finally, the 'angel fruits' would probably be too overpowered to work with anybody but a villain. I can handle nigh unbeatable villains. Hell, they are a staple of One Piece. But when you apply that concept to the good guys? Not so much.
So...yeah. I don't like it.