Just to put the cat amongst the pigeons,,,,,
Andy ,,didn't you have a good greyhound along time ago that took 30,s on the lamp,,,or perhaps it was a mates dog,,,lol
I was fortunate to see a big well known grey a few week back get it's first ever run at live quarry,,,it did superb,,,and on the way back,,sight 3 larger quarry all together and off it went again,,,it missed as it happens,,, a good marathon dog though..
Personally out Of a grey and a collie I would sooner have the grey,,,,,
But I agree with Andy if breeding a collie cross,,,I thing better to go to the lurcher,,espe