Well, we did end up with like 5 team members voting, which is the bottom line, but this could still be changed after all. I know you've given a lot of thought here and since I personally agreed I'm not trying to disparage that.
Again, I too would probably be in favor of not worrying about some things more fluffy like our "people's well-being" or sphere of influence, etc... than functional on these issues. So the real question I think has to be asked, though, is are people favoring the mechanical benefits enough anyway. Because there are some tangible differences - we establish the mainland cities, culture, and commerce quicker, if that's what is viewed as really necessary, though it does cost some production/growth/whatever. For what it's worth, since we'll have a galley, that pretty effectively does prevent enemy explorers from getting through, after the sole Vikings boat at least and also importantly, it denies any sort of trade routes without open borders. The visibility from those cities eventually makes sure we have 3-5 turns warning if the Vikings ever do anything.
But again, this wasn't my hugest concern - what we've got to ask is just for the sake of trying to claim/beat the Vikings to land, are we worried enough that we go with settling off-island.
I also think we really need a holistic approach, which is why I also agree with those of you (I know cav_scout in particular, has been saying again and again

) that we also need time to actually see what is going on and adapt. Who we will actually end up allying/trading with can really influence things - it's hardly worth going all-out to settle against the Vikings if it turns out completely unnecessary, or on the other hand, if we are deciding to go against the Vikings, establishing this early, getting the team on the other side with us, and simply making a go of it is possible. We just don't know yet, and we haven't made decisions on diplomacy. Rightly, I think, let me say that - I wouldn't commit in diplomacy to anything too long-term just yet, but that means we have to be flexible elsewhere. Still, it's coming up soon enough.