An outside the box solution, which may not be what you are looking for, is to have an enemy that paths differently than other enemies. Performing flanking behavior essentially. That removes circling the enemies and creates some cool emergent behavior including the semblance of AI that has teamwork, even though the ai isn't really working together.

You could do something as simple as the way the pacman ghosts work. One ghost sets his navigation target to the player's position, one sets his target to a position behind the player, and one sets his target to a position in front of the player.

If you look at geometry wars enemies you'll get a good idea of how this effect works. With just the blue diamonds (enemies that just follow the player) you can easily fly in circles around the flock. Introducing the green squares (enemies that follow the player and are faster than the player, but avoid the player's bullets) the player now has to juggle the flocking behavior of two enemies. Then you add enemies who just wonder around aimlessly and now the player has to keep moving to avoid blue diamonds, keep herding the green squares to keep them from catching him, and dodge random floating pinwheels.

Your solution is just as viable, just making sure you account for other possible solutions that might also make your game interesting.