“Who is stronger?” – Might versus Magic.

I'm leaning towards this scheme:
All registered players participate. We divide everyone into Strength and Magic. Games are played strictly between Strength and Magic.
Group stage.
Round 1 - random draw.
Round 2 and all subsequent rounds - pairs are formed based on the same number of points scored, repeated pairs are not allowed (in this case, the player(s) with the fewest points participate/are drawn).
We have 9 players registered for Strength and 8 for Magic: should we do 7 rounds of 7 days each, or 6 rounds of 10 days each?
We set a limit on the number of games with one Faction - 3 games.
The choice of Factions is made by the players in the pair independently, immediately before the game: they write down their choices or "secretly" inform the judge.
Playoffs.
The top 4 players from each group of Factions advance. If there is a tie in the number of points scored (players share 4th-5th place), an additional game is played within one group of Factions.
There are no restrictions on the number of games with one Faction.
We just need to decide about the choice: do we write it down or inform the judge...
Option 1: simple Olympic system - 1/4 final, semi-final, final.
Option 2: simple Olympic system - 1/4 final. Then a Super Final of 2x2. The choice of Factions in the Super Final is "secret": communicated to the judge via ICQ, private message, etc. There are no restrictions on the choice of Factions.