I think Henry and Jack's sacrifices must be somewhat equivalent from Jack's perspective.

That's how I felt. I wanted to bap Henry and tell him to quit thinking just about his pain, his loss. You may as well say that Henry forced Jack to kill his own baby by having to stop Henry. That may be taking it a little far, but I think Jack had as much pain as Henry and Henry was oblivious to it.

Razor promo in case you didn't watch Eureka last night.

Jack didn't know how much he was giving up by saving the world. And having learnt that, he really doesn't know.

In the moment, Jack was sacrificing a good chunk of his own family, including his unborn child. I think Henry and Jack's sacrifices must be somewhat equivalent from Jack's perspective.

absolutely. They both lost their wives. yes, Allison's still around, but she's practically a stranger. In some ways, that could be worse. When someone's gone, they're gone; but when someone is there, knowing that you know how they think or what the back of their neck tastes like is a little harder. Kind of like "loved and lost"

Jack knew he was giving up Allison and the baby by going back. He had hope that that family would all come back to him, that it was meant to be, but it wasn't, and by the end of the episode he was realizing that.

And yeah, losing someone when they're gone-gone is different from losing someone when they're still right there, and worse, oblivious to the fact that you lost them. At least Allison gets to go on living.

Jack knew he was giving up Allison and the baby by going back.

I don't think that he did. When he was talking to Henry about the guy tripping and spilling his chili, he acted as if everything was going to happen the same way, so he may have thought that he would get to go through courtship again, and not make any mistakes, but still end up married to Allison.

Yeah, Carter's "there's no way, no how, that we don't end up together" from OiaL does support the idea that Carter thought he could still have a life and family with Allison (and he probably didn't understand that even if he did, that it would come about differently, that any babies would be different babies.

But Henry knows that. Henry also knows that Carter, despite his bumbling, still has a chance at reclaiming some semblance of that future, paradox-free. Carter still has hope. So I don't expect Henry to really be able to feel he's in the same boat with Carter, but I think Henry's act in the end was partly an acknowledgment of Carter's loss.

Also, one thing I thought odd watching, but now realize was a result of his living four extra years in Eureka, was how extra smart Carter was this ep. The lines he was spouting and conclusions he were coming to and equipment he was handling (Carter is putting electrodes on Stark?!) seemed out of 2006!Carter's league.

Cferg, for you I shall chalk it up to needed exposition and take away from it the fact that Carter was on top of the world in the beginning, full of hope and optimism. Which, like I said, counterpointed the ending so nicely.

In last season's finale, at what point in the future did Henry go back to save whassername the first time?

a result of his living four extra years in Eureka, was how extra smart Carter was this ep

I wonder if he will somehow keep that savvy, maybe subconsciously, or if he lost it with his memories?

In last season's finale, at what point in the future did Henry go back to save whassername the first time?

Months, years? Or maybe just weeks or days. He had to lobby to get Stark's job, which Nathan lost due to "Cutting corners on the Artifact", which could take time.

Since Stark losing his job wasn't due to something catastrophic like a death, the DoD might not be in as much of a "rush" to replace him and take their time finding alternate candidates. It took them a month to finally fire him in this timeline, so maybe longer in the alternate one.

Then he had to get Walter's tachy-whatzamahoozit-thingy out of deep storage and in working order for his own purposes.

I wonder if he will somehow keep that savvy, maybe subconsciously, or if he lost it with his memories?

Well, he seemed to still have an affinity for that book of sonnets, although I prefer him not so savvy. Part of his charm.