Worth mentioning, too, is that the most gruesome kill—being burned alive—belongs to Mrs. Lovett. This could very well be a reflection of her villainy being repaid in kind, or, as I've seen proposed, it's a reflection of Sweeney Todd's cock-eyed chivalry turned on its head into something ugly. Like, he expects the men of the world to be vicious and cruel and trample upon the innocent like they did his beautiful and virtuous wife. For Lovett to betray her sex is a step too far for him, it seems.
Also, the above paragraph contains spoilers.