Yep, that's how I felt all along, Grundy is a stoppage beast who is (was) great on the spread from stoppages for the 2nd possession in the chain as well, would run other rucks into the ground.
Gawn is great getting behind the play, which is the main thing I worry about if he is playing forward more, but secondary to that I also worry that the rucks have really struggled to get behind the play so far, it's moving quickly from 50 to 50 and I don't know if Gawn can get to the contests needed. Gawn has also got the bonus that he's a better marking target for long kicks for his own team, Pies didn't even look for Grundy on kick-outs or long kicks.
I don't really like either right now though. Taking away 10+% of their scoring source is still very significant at their end of the equation. I still like Gawn more because he's a much better ruckman, which means more of the stoppage pie, and he does a lot more things away from the stoppage to score, plus, he hasn't looked like utter crap for the last 8 odd games he's played.