I don't know if anyone has said anything about this, but I'd be interested to know more about the Daniel Collins "backstory" to 1840. I'm wondering who Harriet was (besides being his wife) and why Daniel murdered her.
Despite his being a murderer, Daniel is one of the characters we sympathise most with in this storyline. This complexity of character and the ambivalent feelings the viewer has toward him -- we sympathize, but at the same time have reservations knowing that he's a murderer -- is a sign of good character development -- by both writer and actor. I always prefer shades of gray to black and white interpretations.