I have worked with a lot of expensive W.C. females over the years (new blood morphs and unproven we brought in) I would say generally they are very hard to get breeding. Females under 800 grams that come in from Africa seem to breed fine (bush babies they are called they range from 200-800 grams)

The best success i have had with adults is, females that come in gravid and then lay eggs. They seem to feed much better and bounce back quickly. African rats are great if you have a finicky one. The trick is getting the to breed. Usually it takes a few years to get them going.

A friend of mine got a female Volta (huge ball python from a certain area) from Africa 3 yrs ago. She laid 17 eggs when she came in. She started feeding quickly and my friend tried to breed her the following season without success. I got her later that year and tried her the following season with the same results. This year i paid close attention to her, one night she was wrapped around her water bowl during the cooling and i put a male in immediately. they breed a few times over a few months and she just had her pre lay shed on 5/29 .

So they can breed you just have to be patient. I would highly recommend NOT getting them for breeders unless they are something special, since they usually take just as long (or longer) to breed, as a hatchling you can raise up.

Hope this helps
Jon