Hi Brian1
That's a new one on me, never heard of it, but I would guess at some sort of Russian or eastern European sheepdog, just because it looks so much like my Karakachan (Bulgarian sheepdog) apart from coloring.
Mecho is very quiet and placid, likes everyone and everything, and doesn't really put a paw out of line. The one problem I have with him is that if I leave food on the counter he will climb up to steal it, even just a few crumbs. He's even been known to walk off with a bag of frozen peas when I was searching for something in the freezer. The bin is now hidden in a cupboard because he can smell food from yards away. Other than that he's a great dog, hope yours turns out to be the same.
I suppose one con with these dogs is that any health problems will cost a fortune at the vet's, just because of their size. I can't really think of any others.
I'm told sheepdogs generally are very loyal and protective, and just the size of him scares strangers away. When the lad from the electric company came to read the meter last month he said we didn't have to pay any more because he was too scared to come in, but sadly he was joking so we still have to pay lol.