I use a collie x whippet x greyhound.. Have just finished my first full year with her.
Not only is she catching bolters, retrieving live to hand, she is also working as a retriever at night whilst shooting from the land rover, just point the lamp in the direction of the kill, and bingo....jumps out the window, returns etc..no more fence climbing.
Looking for another dog this year to support her...may go for summit with a bit more whippet..just for the hell of it.
As for speed.........ask the boys at the Scottish Lurcher shows......
Bess.
I also have a mate with a c