I'm leaning toward Woodhead. The Chargers always seem to be behind, which is an ideal situation for a check-down back. It could go either way, though, as the Panthers are actually pretty bad against the run. It wouldn't surprise me to see Gore top 80 yds and grab a touchdown. But, as you said, they're great against the pass and at making plays on the ball, so multiple turnovers by the Colts would not shock me, which would probably kill Gore's potential. The Colts are excellent at digging themselves a hole.
Woodhead is probably the safe play. It just feels ridiculous to bench Gore when he's actually playing well and is probably still one of the most effective backs in the league. It's just that the Colts suck.