I think that's just internet hype, to be honest. I know there was an article by Scott Wheeler (who's a total hack) about their shots, but it totally ignored Bellows' ability.
Wahlstrom is certainly up there, don't get me wrong, but he's been overhyped a bit, I think. His release isn't as quick as Bellows' and Kieffer also has a harder, more accurate slapper. Wahlstrom does have a lot of the same weaknesses as Bellows, though, which is often overlooked.
Wahlstrom is good at changing the angle of his shot, like say a James Neal, and he's probably better at this than Bellows, but that's because Bellows doesn't have to. He has a Kessel-like release and can get rid of it before you realize its on his stick. Wahlstrom is slower at handling the puck and just isn't as lightning quick as Bellows.
I think it will be abundantly clear when both make the NHL that Bellows has not only the best shot, but best array of shots in the organization.