The thing with rambo sacus is that they're extremely viable relative to other sacus. There's no choice because rambo can just do everything. In terms of the whole game, rambo sacus aren't really oppressive or really all that viable. They get rinsed against direct fire t4s (another good friend uef hole in the roster) and you just need to work on not letting 50k mass of them conglomerate in one spot.
Even with that, the value in rambos come from the fact they are basically a fatboy in survivability for way less cost, way faster, way easier to maneuver around enemy defenses/armies, and on top of that can plop down emergency sams/shields/arties/pd depending on the crisis they need to respond to. A fatboy is irrelevant for any of that because you need the t3 engies around it already because a fatboy exists in perpetual crisis situation because it's aggressively mediocre as long as nothing about percies gets adjusted.