
I think if anyone is planning only one litter or hasn't the storage facilities for a whelping box to lie idle for a few years at a time then disposables serve the purpose well :) The snowsilk pro boxes are wonderful, easy to clean and robust but are an expensive outlay which may not be necessarily used again.
I used the newborn disposable box for my girl's first litter and it was still in good shape when the pups reached 5 weeks. It has a waxed base which is easy to keep clean and remains dry however during the actual birth I'd suggest anyone going down that route uses a large sheet on the bottom covered with bedding and the sides then draped with the excess material :) This prevents any staining or spatter on the interior sides of the box so that when everything is tidied up and mum nursing her newborns the box is fit to be seen by anyone.
HTH, Teri