I think if we utilise him in some games in the second row it could be quite effective. Maybe for his second stint off the bench late in the game against a weak 3rd in defender every now and again?
Typically your 3rd in is a half anyway. And Sam does do pretty well isolating them, driving them back, getting good metres and a quick PTB.
I don't know if he'll be getting a "second stint" though, especially if he starts off the bench. If he comes on, goes off, then comes on again, that's 3 interchanges used up just for him. It's likely with the new interchange rules the benchies will get one good stint and that's it.