I have experience of a Grey with a half lab (my old girl was a mongrel but dad was a full working lab and she was basically a labrador)
My parents rescued a retired GH 2 years ago.
My brother has 2 border collies.
My son's stepmum owns 2 retired racers and fosters GH regularly (as well as running a dog sitting business)
This is all relevant 
So, GH had never mixed with other breeds before. He is fantastic around other GH and is often cared for by my son's Stepmum. He adores her 2 boys and has always reacted positively to other GHs in her care.
A careful introduction with my girl was a bit ropey but ultimately he wanted to be in charge. He would always stand over her and get himself inbetween her and whichever human was paying her attention. My girl had an excellent temperament and was never aggressive. We took them out for a free run in a dog paddock and she blindsided him as they both ran for a ball, resulting in him pinning her to the ground by her neck. I thought he was killing her but he'd not made a mark, it was a warning and she was happy to remain in his company (different matter with me as I was nervous!). Slow and very controlled introductions resumed shortly after and they were then the best of friends forevermore, until my girl passed away a few months ago.
Brothers Collies... one is a grumpy git who isn't good with other dogs. The other, younger dog, lives and breathes for ths older dog. After one very controlled introduction in the dog paddock it became clear the the older Collie was too reactive which spurred on aggression in the GH. So unfortunately, even after 2 years, we have not allowed further contact.
GH is wonderful family pet and adores all humans. He really does not like strange dogs, particularly hates little dogs, which is a problem on walks (he wears a yellow lead to alert other owners)
obviously each dog is different but that's my experience, hope it helps.