Mech shaman, which is a completely viable ladder deck, still runs Fel Reaver.
If you don't think Grim Patron is imbalanced, you're absolutely crazy. The only real question is, is it imbalanced enough to need a nerf? It's not as bad as pre-Leeroy nerf Miracle was, but it's definitely better than post Leeroy miracle, and post-Leeroy miracle was still strong enough to get Auctioneer nerfed.
As for Thaurissan, his inclusion in freeze mage is really all the proof you need of how overpowered he is.
Except combo decks like freeze mage or inner fire priest are fair, and allow your opponent chances to interact with you and interfere with the combo. Decks like leeroy miracle and patron give you minimal chance to interact with them and basically no response to the combo.