Jungle Wars: Upgrading pterodactyls

Is it worth upgrading pters? These two screen shots show the difference in values.

Here is the lowest level pter. Below is the highest level.

In my experience, the upgrades are not worth the enormous cost. The bird that cannot get the job done at level one is going to fail at max as well.

If you attack en masse with eight birds, you still need healing spells to get through the ack-ack, so the level is not terribly important. And if you win with eight birds and some spells, the system is not going to give you many clan points. It might even penalize the clan for overkill.