I approve the idea. It is simply weird that a battlecruiser charges its engines up with the same speed of a fighter, considering the loadout, difference of mass and whatnot, am I right?
Instead, I'm not really supportive of a better CE charge speed for pirate ships. That way people would prefer them over other types. If we would have to do as you say, I'd propose to enhance other ships' statistice, to balance out.