[Makhil]

My kiss solution would be to calculate roids gain, xp gain and salvage based on total attacking ships value vs total defending ships value.

-The smallest the ratio the more xp for the attacker (no xp if the ratio is too high... even negative xp if it's utter bashing)
-The smallest the ratio the more roids you cap (with a real difference between the 2 extremes)
-The biggest the ratio the more salvage for the defense