I experimented with this myself and I saw that the rate of goals produced from this were about the same and I saw that having my specialists taking those set pieces gave a better chance of producing a goal. The logic is there, having your GK come up so all 10 of your players are available but the game rarely recognizes this advantage in recent updates. I remember when I started playing last year though, it seemed to be the best option as the game would seem to just allow GKers (since they technically dont have a finishing/crossing attribute) to have specialist quality set-pieces. Idk how many times I lost or drew a league game from an opponents' GK rocketing in a free-kick like he was Neymar lol