actually as of right now, it would be way too unbalanced. Cause when the UC guys were making the units they made attack powers adn armors and everything WAY too high.
The ZAFT units as you probably already know, they are better then the higgy and vagyr units, but a single group of GINNs can easily be killed by the higgy or vagyr.
On the other hand the UC mod, a squad of GMs can take on a higgy BC easily and if you pit them against zaft, 2 squads of anti ship zakus can take out the minerva with little trouble.
If however someone had a lot of time on their hands (A LOT) they could probably balance the UC units to the ZAFT units.