As for the trade, having a 100% guarantee on the genetics, I say its not bad.

Checkin your current collection, you already have a handful of poss het clowns and a 100% het. Its not bad adding another het female and a proven het male to go w/ it, that is if you really intend on having a sure shot in producing a visual clown. But considering the other morphs that you have, you can produce other awesome combos that you can eventually trade up for a visual clown in the future. Try to think of this, pewter x spider, pastel yb x spider.. the list goes on..