Hi Scolly,
I;ve never used carophyll pink either. But it is what they use to give the 3r2's there bright color. Of course the fish has to have the genetics to be able to utilize the color. There are definitly health issues with carophyll so it wouldn't be a good idea to experiment with it on your prize show fish.
I have never heard of any health risks associated with NatuRose though. It's a dried algea and has numurous health benefits and the only problems I've had with over using it are that the fish don't like the taste if too much is used and it will give hte fish an unatural look. I use 1 tsp/lb of beefheart and will start cutting back on the amount I feed adults to avoid the over colored look. I have never heard of feeding it straight with only oil to hold it together either. I think that's way too much, but not for health reasons.
HTH
Kacey