I think you meant to reply to the post on my own journal.

As for the studies, it's probably cheaper to hypothetically offer people upgrades than to actually do so (and I'm not sure how you get consent forms handled in the latter case) but I have no particular reason to doubt their conclusions, namely, that people won't usually upgrade to first class if it means leaving their travel companion behind. If nothing else, this sort of thing is sure to irritate the other person, and that's just going to tank the vacation.