In terms of position, I have both Teixiera and David Wright, so I'm already covered at both 1B and 3B. I also picked up Smoak, so I already have another good backup at 1B - I guess that's one reason to stick with Beltre.
This league uses three Util positions, so I can still make use of three 1Bs, but I do like variety.
That said, I gotta admit I have more faith in Dunn than in Beltre. Tough decision!