Nod has the advantage and disadvantage of a higher ceiling with HoN, much likes the weapons factory.
Are we seriously going to have to mention every balance to you 'imbalance' in equivalence to winning a game on Renegade X?
Because funnily enough roofs don't come into the realm of mining, roofs comes under the pretense of Actively Defending for large games. Which also includes considering where all the mines are and actively going to that area to check up on any potential infiltrators, suddenly the mining problem comes under actively defending the bases' problems.
You'd be surprised how many GDI and Nod you can come across now, they're mental, the GDI ones are a lot more noticeable so the mine limit is fine as it is.