I may write up individual Mantis issues on these, but I thought I would put them here first, and then post them if requested.
1. They push around stuff, especially Spirecraft Shieldbearers. I guess the issue is that the Shieldbearer push priority needs to go up some (harder to push them around), and the friendly enclave push priority needs to go down some (so they won't push away things you have strategically placed)
2. They frequently move around when defending a planet (jumping from shield to shield in a random fashion), which doesn't help much, and just wastes CPU cycles. Can you have it be like the auto-knowledge gather shield seeking behavior, prioritize shield that contains the command station first, and as long as the shield they are under (if any) continues to satisfy that, they won't try to move to another shield?
3. They are too timid. Yea, I know they won't charge into a battle they feel they aren't safe to go into, but right now, that threshold is too low. They are pretty durable units, and can very likely retreat successfully unless very, very out-gunned. Can the ratio of "am I too out-gunned?" for them be brought up some, considering that they are tough enough to retreat successfully in most circumstances?
4. When the "prioritize homeworld" flag is turned on, they seem to prioritize it even if there is nothing threatening it and nothing nearby threatening it, to the exclusion of other behaviors at many times. (This one I have not put as much effort into verifying, it may just be due to #3, but this point isn't an issue at all directly)