I suggest that RAS will reduce the mass consumption costs of nearby buildings to zero. ARAS reduces mass and energy consumption of nearby buildings to zero. Units and in particular engineers derive no benefit. SCU's provide a 50% reduction instead of a 100% reduction.
The radius should be pretty small, so that at most 4 medium or large buildings can benefit from its effect. This would yield a benefit of 64 mass income from mass fabricators, 84 free mass with T3 factories, or at most (I think) 160 free mass with 4 strategic missile launchers. This is significantly more than now, but, it requires your commander to be in a specific place, don't do much at all, and a specific arrangement of buildings.
The most interesting benefit of this form of RAS is that it renders nearby buildings immune to mass stalls, and in case of ARAS also power stalls. An ARAS commander will never suffer shields going offline. After your eco is wrecked a RAS commander can allow mexes and other buildings to upgrade for free.
However, there is more counterplay as well. All benefit are situational. When you are chasing the enemy commander away, RAS does nothing anymore and the eco might in fact stall right away once the buildings start drawing real mass again. The "free" shield cluster will also not operate if it is destroyed by an intruder.
I'm by no means a FAF or balance expert, but thought this might be an interesting idea. I cannot really defend or speak on its impact on balance or the metagame.