1
Remember that AL league with the Gonnie Garko team? Getting a qualified 1B was an absolute nightmare due to recent retirements/DH career changes and FA moves from the AL to the NL. You're right about 2B in this regard, and if Figgins is something like +5 or +10 at 2B, then statistically the whole thing is a coup, with the icing on the cake being that a couple of our best ML-ready (or nearly ready) prospects can man 3B if needed.
I tend to agree with you about the overall defensive benefit of swapping them. Lopez is almost certain to gain significantly, and I would imagine that Figgins doesn't lose much in the way of 'real' defensive contributions. Plus it more clasically utilizes their particular talents.