I own griffons and for user who trashed on them, I personally never had one problem. They have hit trees, urban rails and have 150+ days of use and they are still going strong.
That being said the FKS's are sick bindings and I have heard a lot of good reviews, but I don't have first hand experience.
If you have the money go with the FKS's, but if you're stuck on cash the griffons are not a bad binding at all.