I've never quite been sold on Martin as a forward. When playing for the Suns it was the position he played least. Most of his time was spent behind the footy, on the wing or in the middle. Forward was only ever pinch hit for a qtr. I think by now we've seen why, he only shows up for qtrs at a time now and then as a forward.
Maybe with McGov out he's worth trying down back or as a marking winger. He's a good intercept and a good kick, we could use his class coming out of defence or as a marking wingman who drifts forward.
His best role is probably that high half forward role that fisher is playing at the moment. Not suited as a deep forward where we have been playing him. Doesn't have the nouse and is a really poor kick at goal. Also doesn't have the tank and accumulating ability to play midfield / wing. Half-back could be a go like you said but we are stocked in that area so don't really need him there.