I have to agree with Jon -- many "super" males don't excite me much, because, while he is admittedly guaranteed never to throw you a normal baby, all he is guaranteed to contribute to the pairing is a single yellowbelly gene. For me, I can't think of a reason why I would use a male yellowbelly (valued at, say, $650-750 market value) when I could pick up a smokin' male pastel yellowbelly for ~$350! Yes, he can throw normals while the ivory can't -- but, he could also produce pastel yellowbellies, while the ivory can't, so whatever female you pair him to, he has the potential to produce more exciting offspring than the ivory.

Additionally, I would be a little bit hesitant to use an ivory whose parents I had never seen, because for all I know, the yellowbellies used to produce him -- and, presumably, the yellowbellies he will produce -- might be very poor examples of the gene. With the (more affordable!) pastel yellowbelly, it's easier to see the quality, IMO, to ascertain what you're really working with.

... Of course, all of that assumes that your goal in breeding these snakes is to produce the nicest example of the most "high end" morph you can reasonably afford to. Not everyone has that goal. If your goal was to produce as many morphs as possible for re-sale, it might be better to use an ivory since then you are guaranteed not to produce any normals, while with the pastel yellowbelly you might "whiff" and get ALL normals. Or, if the ivory is more of a pet or a showpiece than a breeder/investment, and you really want his babies because you like him, then your decision is easy.

Was that long-winded enough for ya?