But is it 'wastage' if someone , as you said Whin, doesn't need a pacy dog?
To use word 'wastage' when describing pups is wrong IMO, if bred from a sighthound (in this case greyhound), the litter is just divided in their form and speed... One mans meat is another mans.....!
Also, do you think a havier type of first cross that proved its worth would be ideal for a second cross back to greyhound or 3/4 bred dog? Advantage being the dog would have been properly tested in the field but still produce heavily collie blooded lurchers.