Quick question about the invisibility thing...
If others can see them, since they're merely vibrating at superspeeds, does that mean they're really invisible?
Magneto can bend the light around himself, to make himself invisible to normal eyes, but if someone notes the trick, he's not really invisible.
I'd wager that the Superspeed blur thingy might work on Wolverine, or Hulk and Thor, but not Magneto, or Surfer or anybody with specially tuned senses.
Thanos might be able to pick up on it.