You know, I think the entire S1 of Atlantis is far darker and grittier than the entirety of SGU so far, yes I went there. I know it's not new ground but seriously: Sheppard killing Sumner whether out of mercy or to protect earth is way, way darker than Chloe's already dying daddy sacrificing himself (heroically) for everyone else. The Storm/The Eye/The Defiant One gave me actual chills it is so gripping and dark, a guy shoots himself became he thinks McKay of all people wants to fight but can't because of him. Again midseason Shep kills more than 60 men without blinking (a trait he shared with Jack, but we have to forget that as well according to Nu SG). The Hoffans, Micheal, the replicators, Inqusition, Teyla and Ronan's potential issues, characters that actually did die or were lost during cliffhangers etc all of those lead down a potentially awesomely complex path that TPTB at their own admission mostly ignored in favor of McKay (hilariously) freaking out yet again. And Yes, Miller's Crossing is as dark as anything else on TV, and could have been an amazing character arc but got 30 seconds of angst before wrap up. TPTB act like the could never ever have done dark arcs in the other shows, but the stories were begging for them to go there..........
And you know, as much as I was desperate for some Shep backstory over the years I would have rolled my eyes if it had been in the pilot ala Scott's many, many DRAMATIC BACKSTORY ISSUES because caring about a character has to come over time.
And "Letters from Pegasus" is such a good episode because we don't have to endure kinofessionals all the fraking time. Used once IMHO it was effective, used 5 times and ep was snooze worthy.