I know I have used a FSDInterdictor once or twice some years ago - when you had to do specific mission types for promotions. I can't remember when I last had a KWS fitted in a ship, more recent than the Interdictor but certainly more than a year. (Those over several accounts.) So I am merely indulging in conjecture as to binding both to one button.
The KWS is well worth fitting. I made 2.5 billion cr bounty hunting last 2 week, about 1/3 of which came from the KWS. Those people that say that the KWS is a waste of time are nuts.
Exact figures from my last cash in:
1,865,834,496cr normal bounties paid at the station
405,496,704cr from KWS paid at the station
60,221,34 cr paid by Interstellar Factor
315,496,521cr paid by main faction at IF station
2,647,049,602cr total
781,214,566cr total from KWS = 41% increase
Cost of KWS 121,900
Return on investment 640,865% per week or 7,690,381% p.a.