i think, as long as l&c know they'll be together, they'll be happy.
that said, i can't see either of them choosing once a year for eternity over an unknown but more natural lifespan. continuity is important, imo. more, it's what we're used to, in a very basic sense. i think it would take a lot of convincing to look past that, and i'm still not sure i'd see either of them choosing it.
as for an earlier lois, she'd have to choose to be with clark. then you're getting into all sorts of things with lois accepting clark as her soulmate, and then accepting that she can only see him once a year.
there's also, as mentioned, clark talking about living in the moment and taking things as they come and trying to have a normal life together, despite all the weirdness in their lives.
that's the one place where you might find lois starting to agree with you. because, in that ep, she's afraid that she'll grow old and clark won't. if this eternity deal includes her not aging, then that might be enough for her to have second thoughts.
i still think, in the end, she'd choose a lifetime over one day a year for eternity, but i do see that there's a reason for her to give it some thought.
Paul
