My mate runs a colliexgreyx salukixgrey, and it is 9 years old, and it still can knock over 20-25 rabbits in a night.It as great stamina,good retriever and quick recovery rate.And it as stayed sound for years. Dont think you get will many lurchers that ( can+want to) do that amount of work at that age. So in my book this is what i would call a(very good x) as a lamping dog.
think youve answerd the question with your mates dog bird
but as for what x i think it is more down to the individual dog and the owner(conditioning,training etc)
that dog sounds a topper by the way to still be doi