Faithful Hound is strictly better than Baker. And with +Buy it should be pretty busted, yeah.
Notice that the attack on Sinister Plot is one card stronger than Urchin. It's half of a non-terminal Mercenary attack. It wouldn't really be worth buying a lot of if it only worked once per turn, but could warp the game. Later on, you might have to decide between, say, $8 or playing your two Sinister Plots back and hoping to get the $8 back. It could be pretty wild. Or you might just draw your deck from a three-card hand every turn and play your only two SPs.