Yeah, sensors are slightly different from FTL drives, but when talking about them, they're linked. If you have really fast FTL drives and short range sensors, it's a lot easier to raid v. long range sensors and slow FTL drives. If I can see you comming two turns away, I can move reinforcements. If the first I know that you've jumped in system is your emergence patern, I'm sorta screwed. It's like to communication speed too. How fast can I react to a problem. And by fast, I'm thinking distance.
One idea that I've seen people play with that looks really fun is larger stars give you boosts to speed, meaning that a super giant, such as Arcurus (screw spelling) might be strategically imporant. Or make it easier to 'lock on' to big stars, but if you're bold AND darring, you could lock onto a planet.
Based on the raiding that the Federation did, I'd suggest a few options:
1) that it's just a jump and you're someplace else with the Federation being able to come and go from a sufficently large number of places that they can hide.
2) No FTL comms and no FTL sensors, or just short range sensors. Here you have a warp/hyperspace idea and still have some surprises. Like posting a defensive fleet in hyperspace. Mousetrapping the raiders:)
You could borrow the mechanics behind VBAM:FASB
-K