Quote Originally Posted by Skandinav View Post
Your question sound as if within the boundaries of the theory stating that the quincunx formation was held even after the armies had clashed; the mainstream view on the quincunx though is that the three battle-lines was joined ( probably with small intervals between the units ) before the battle, and that the maniples were only for temporary maneuvering.
So the quincunx and regular battle lines are actually part of the same system, the triplex acies quincunx, although they have been used both together and apart.
Goldsworthy categorically rejects the idea that the quincunx was for deployment/movement only, and that they were joined together in battle. I find his reasoning persuasive that arraying troops takes a lot of time, and it's a further waste of time to deploy them in the quincunx only to collapse the gaps once battle starts.

Quote Originally Posted by Che Roriniho View Post
Going by this then QS, How would your 4 legion system (I have doubled up everything in the Socii, and an Allied General to keep them under control) work as a quincunx? Thanks so much for everything btw.
Still the same as the Camillian/Polybian ones - Romans in the centre, Allies on the flanks/wings. If we go with a three-unit legion (one Aquila, one regular, one "veteran"), two of those in the centre with units of allies outside them. Allies for all your skirmishers and cavalry, too.