I´ ve always been a bit disappointed that Torps and Missiles function so similarly. I´ d have prefered a Torp to have been a 2dice attack that, if it hits, has a catastrophic effect (with missiles being much as they are now or potentially with more dice for a smaller catastrophic effect).
But it´ s too late for that until 2nd edition...
So as a way to differenciate them for me would be for torp/missile attacks to gain or lose 1 attack die depending on the target. This could be by base size or by agility. Disclaimer: I haven´ t tried either yet...
So torps would get an extra die against large bases and lose a die vs small bases. E.g. A proton torp would be either a 5 die attack vs large targets or 3 dice vs small targets. Alternatively Torps could be +1 die vs AG 0 or 1, and -1die vs AG 2 or more.
The missiles would be the opposite of the torps. +1 die vs small bases, -1 vs large OR +1 die vs Ag2+ and -1 vs AG 0 or 1.
There would be no points cost changes required, with a relatively simple to learn implementation that should be closer to how Xwing the computer game defined them....