Sorry I know this is a older thread. I've been away a while. I did some crosses and was successful getting colored sultans by 3rd generation. Then looking at all my chickens I decided I far preferred the white ones lol.. I did keep one I call a dalmation and another who is a dirty white. I have a few others who are crossed but look like pure sultans. I can tell by their egg colors since I used giant cochins as my cross and my hens now lay beige eggs if they are not pure.
I also crossed into a bantam cochin frizzled. I have two little tiny frizzled half sultan hens now which my rooster is completely ignoring I think.
I kept as my breeders during my cross the ones with "puff ball" crests. So my sultans look a bit different than those you have pictured. Even my rooster has a good puff ball shape to his head. I hatched a lot and culled heavily (culling means I sold at a animal auction). As a result of crossing I have not on super broody hens but they are larger and lay a LOT of eggs.