Bear in mind, that although a lurcher can be a greyhound crossed with just about anything, it is 'technically' a greyhound x border collie.
I love both breeds and have a border collie but bear in mind that most lurchers will have a very, very high prey drive.
Some lurchers have very little prey drive, but that is not usually typical.
Like the parent breeds, the lurcher is a working breed.
A dog with high prey drive can be both a blessing and a curse.
Another thing to consider is that a high proportion of rescue lurchers will be ex working dogs.
If a lurcher is an ex worker it will not be safe around any kind of small animal including cats as it will chase and kill and small dogs from a distance.
There have been many cases of sight hounds mistaking a small dog at distance for prey and ipoften, it doesn't end well.
I do not personally believe that mistletoethrush's dog is an ex worker if she 'tries not to look at sheep'
Predatory aggression is an enjoyable behaviour for a dog, sad but true.
It is incredibly difficult to stop a high prey drive dog engaging in chase and borderline impossible to stop a dog with a high prey drive that has been worked and rewarded for the behaviour.
I would not look at the 6 month old shepherd either.
At six months he or she is likely just approaching adolescence.
The mix of hormones, that desire for independence and boundary testing coupled with the stress of settling into a new home with people it doesn't know.
It is not something I would do.
I would get either a well bred puppy from an ethical breeder or a much older rescue dog 3 years plus from a reputable rescue who home check and extensively temperament test the dogs as previous owners frequently lie about their reasons for re homing.