For most of my game, two or three ships of this fast class of boarding vessel form my entire fleet.
Two things are imporant here: The ludicrous top speed of 281 km/h and fast response time with new commands every 4 seconds.
I'll take most settlements that don't have airships for their defense (and they usually won't, because they don't have any ships fast enough to get there) in one fluid motion of flying to the buildings, dropping off the troops and retreating out of weapon range.
Even when there are enemy airships present, one or two Invaders with Air Dragoons will manage to capture most medium-sized vessels.
I like collecting all my captured enemy ships in one location - towards the end of the game, they won't all fit on the map.
So pretty qicked, i had to expand it out a bit (one extra barracks) to really get it kicking but its great. Do a larger zeppelin mod to back up the little ones as well and yeh you can have an entire fleet of just boarders.s