About a month ago the impeller on one of my 625 Ilmors gave out. I tried a blue one in it's place. The pump was useless with the blue impeller in there. I mean it wouldn't draw ANY water.
Put a new Merc impeller back in and everything was fine. For my application the blue one was useless.
On the other hand a friend with a 37 Sea Ray tried one in his 454 and it's worked just fine. It runs slightly less pressure and a little hotter than the merc impeller. But so far so good.