I've been levelling a character with a stable group of 3 players + 1 companion for a few weeks, and we've been baffled by the inconsistent scaling. Generally, missions are easier as a group of course, but sometimes a mission will be way more difficult than expected, with vastly more enemies than you encounter doing the same mission solo; often Elite mobs in every fight--sometimes 2 or 3 elites at once.
Last night, we went into "Thus, Always, to Tyrants" and it felt like we'd wandered into a Flashpoint by mistake. We have had similar experiences with a some other missions along the way... I'd just like to understand what the scaling mechanic is, whether there's any way to tell when we should just do a mission solo rather than spend 5x longer, die a lot and have huge repair bills.