I was playing around with a level 9 Rankulas last night to see how strong its nanite swarms were. I had 2 points in Combat Nanite Swarm, 4 points Support Nanite Swarm, 1 point in Assault Nanite Swarm, and 2 points in Greater Nanite Swarm.
I parked the Rankulas at the star (so that I could have essentially unlimited antimatter) and started pushing out nanite swarms as fast as I could. I was able to keep 6 combat swarms, 3 support swarms, and 2 assault swarms going continuously (a total of 11 swarms). Then I fired off Greater Nanite Swarm and the 11 swarms were sucked into a single greater swarm.
The greater swarm had stats similar to a level 1 capital ship - around 3000 health, 1500 shields, and did about 40 dps (26 x 1.55 i.e. a 55% damage output). The problem is that this greater swarm is much less powerful than the 11 swarms sucked up to create it. The 6 combat swarms were each doing about 15 dps (7 x 2.25 i.e. 125% damage increase) which is more than double what the greater swarm does. Worse yet, the greater swarm doesn't have a repair ability so I lost 60 hull/sec worth of repair (300 x 3 / 15 sec). And this doesn't even count the 2 assault swarm that I also lost.
After 3 minutes, the greater swarm disappeared in the same way as the other swarms. It didn't have any advantage in this regard over other swarms. Overall creating the greater swarm greatly reduced the effectiveness of the Rankulas over the next 2 minutes (until it could put out new combat, support, and assault swarms).
I also tried just creating a single combat swarm and then turning it into a greater swarm. This was somewhat effective as the new greater swarm had about 2.5 times the hull and shields of the combat swarm and did 27 dps (26 x 1.05) verses 15 dps (7 x 2.25) for the combat swarm. However, this is a pretty small benefit for a level 6 ability and once you have 2-3 swarms on the field, the greater swarm quickly becomes less effective than the swarms it sucks in.
The Rankulas is a pretty good ship (especially the support swarms) but I'm missing the purpose of its level 6 ability. Does anyone have any insight into this ability that I've missed?