I was also, and remain, indifferent to the 1840 storyline. It was basically, to me, a retread of both 1795 and 1897. What made it watchable to me was Virginia Vestoff as Samantha Collins. Everything about her was perfect, from her character, to her acting, to even her hairstyle. She was the ultimate Queen of Mean. If she had gone head to head with Angelique, she would've won hands down, and wouldn't have needed any supernatural powers to come out on top. Too bad they had her flake out over the return of Quentin's undead past love.
Maybe this is what you meant with the "flaking out", but Samantha always struck me as someone who's not very bright or determined, who compensates for that with a lot of self-righteous bluster. She acts very defiant right up until the point when someone actually challenges her seriously, then she plays victim. She's a house of cards. A good character, but not a "strong" one, to me.
As for 1840 being warmed-over 1897/1795, one definitely has to try to look the other way on that, to enjoy the storyline. Maybe it's just me, but I can almost feel Jonathan Frid's weariness as he trudges through another long storyline taken from other storylines. For me, it was a given that DS wasn't going to do anything original by this point, so the best we could hope for was one last hurrah, where they plunged us back into an atmospheric past era, and shuffled all the reused plot elements so that they weren't too close to the originals.
This beats Jeckyl-Hyde and Rebecca ripoffs and asthmatic invisible monsters and cheap insufferable pigs, I think. (No disrespect to any fans intended.) DS seems to "wake up" at that moment when it goes into the past, including 1840. I get that "oh yes, I remember now why I like this series" feeling. Mr. Frid gets reanimated, too. At the start of these past storylines I get the sense that inside he's saying "Finally, something for me to sink my teeth into again!" ...and now that I've noticed the pun in that sentence, I'm declaring it intentional.....
Wouldn't it have been fascinating for 1970 Barnabas to stay out of the picture, with Julia being asked to fix everything in spite of 1840 Barnabas?