I know berserkers who get an R1-2 from Apostles at their HW each turn for their joint scoring using the Apostles ships. I tend to stay away from trimming. So each migration nets you only 8 pts. Also if you have robotized industry worlds you can keep building robots and migrating them the whole game. Make sure you have left at least one Ring 1 world with carbon based life forms - migration of 30 robots will kill another 60 people for an additional 120 points.
Timing is a critical issue, though.
This happens even if they exceed the normal population limit of the world, and would have died off anyway. Instead, it runs around admiring the newly sterilized world, giving the berserker an extra five points a turn for a robotized world, starting immediately. This also works if you have two fleets, and one robotizes while the other bombs. Hope you find this useful and interesting.