In my opinion its a waste of a good bitch when there are still a few good dogs around to use (agreed there are not many but there are a few). Fine to use a plummer dog over a good bitch of any other breed or type, if you wish to create a 1/2 or 3/4 bred, which appears to be your preference, but to do it the other way round is just plain stupid.
I noticed Millet was looking for a plummer bitch to use his dog over in order to keep a pup himself - he could have chosen to use a working bitch of any type or breed, but he is looking for a plummer (wonder why ) it might be rare and diffi