It wont make too much of a difference really. Currently there are only 3 recruitment slots per province.
With this system 1 region factions will only be able to recruit 2 units (so 1 less) minimum. The player may be able to recruit more but will be able to recruit less in newly invaded provinces.
We may still need to tweak it further if the AI is handicapped too much by it. But need to test it thoroughly first before we made decisions on it.