I haven't actually run 2nd edition yet, I'm currently running a Midnight game.
But in 1st ed, I used a slightly more streamlined system where if it seemed right then it works. That and we just assumed that everyone was on the same "elevation" for the purposes of the map.
I don't have ACTA so I'll use B52ed for my space battles. I have thought about purchasing it, but I don't know if it's worth it just for the large battles (which I think it might get handy), I'll just do really large battles narrativly (also, large battles will be very scarce in my game, unless I let them play EA Officiers someday).
I have played B5Wars, whose minis looked exactly like CTA, and tried to integrate it in the roleplaying game. Much too complex... Roleplayers are roleplayers and no wargamers.
I'll use the 2nd ed spacebattle system (one of the main reasons why I bought the 2nd ed, just to find out that all previous ships are 100% incompatible), since itsrange bands and orders system are abstract and detailed enough so that it is playable in an RPG and doesn ot turn it in a COSIM.