I'd say Stützle's game should suit the smaller ice surface better than Byfield's. Byfield's the one I'd be more concerned for, you can't just score in transition at will like he could at CHL, unless you're at McDavid's level, which he's not. Stützle's able to manoeuvre in tight spaces much more effectively.
I'm glad someone else has noticed this. He's great on the rush because his straight ahead speed is so much better than most everybody in the OHL, but Byfield skates into a corner if he can't get it to the net and then is outmuscled by 5'11" defensemen, and the puck ends up going the other direction again.
He's got a great skillset but I really don't like the lack of assertiveness/killer instinct, and the lack of zone control that Perfetti, Rossi, Stutzle and Lafrenierre bring to their games. They get the puck and they don't want to give it up until they see the highest percentage play. I think that mentality changing is going to be a major factor in what he becomes as an NHL player.
Stutzle is going to be a multi-directional threat in the NHL whether he's a center or wing. The kind of guy you can count on for controlled zone entries, possession, and cycling back into his defensive zone with the puck when the neutral zone is clogged up. I'll take that any day.