one of the things that amazed me in Allegiance is the radar signature
each ship has a signature value, which will increase if you mount things (shields, missles..).
There are stealth fighters with a very low signature at the cost of a very light armor, you also put missles and shields in the cargo to reduce it, and mount stuff only at the last minute. you can also use cloaking devices, which reduce the signature.
Depending by the loadout they can fit various roles, but usually they are effective to infiltrate enemy systems and destroy their miners/constructors, or you can use them in combat to make sneak attacks, for example to destroy bigger ships, like gunships, which are well defended by player controlled turretts, without being tracked.