Using Advent mines for assault  doesn't work all that well once your enemies tech up their armor later in the game but early on its pretty awesome. I assaulted a pirate base with 3 drone hosts, 1 mother ship, and 10 light frigates. The drone hosts had 12 mine squadrons ready to go. All I had to do was lay the mines about half way between the attacking pirates and my fleet on the edge of the gravity well. I deployed the second wave of drones right on top of the pirate fleet. I destroyed the entire pirate defense fleet in about 4 minutes time. 

I've used the same tatic to defend gravity wells from three or four bar raiding parties with two hangar defense platforms and a basic advent starbase. 

The mines take a few seconds to aquire targets and they arn't the most efficent at selecting targets but they get the job done. 

I also found that when invading an oppsoing gravity well and there are no defending ships the  drones could quickly establish a defensive mine field to cover the phaselane against enemy reinforcements. 

Once you add some support crusers and flack frigates to the fleet you can use the mine squadrons to take out mobile defenses, estabilsh your own defenses against reinforcement then switch over to bombers to take out everything else - all from the comfort of the perimiter of the gravity well.