Fill4Me and control + click can load defenders with regular ammo (up to 1 full stack if control + click). Once they run out, they can't attack; if they benefit from better ammo it might be worth it though. Mining and re-placing them with Fill4Me disabled defaults to the infinite defender ammo.

Un-researching and researching follower count or defenders in an existing Editor Extensions map can mess with follower count. Sometimes it will be stuck higher than 3 when all but defenders are removed. Sometimes defenders auto-destruct with "Robot limit reached!" when defenders are re-researched without follower count 1.

Some mods affecting spidertrons work on Followers+ too. Followers+ leave spidertron corpses if the option is enabled in Spidertron Enhancements (nothing salvageable since they lack equipment). Spidertron squad control can select followers without needing to pick a specific leader. Spider sentinel selection seems fully functional as well; followers in sentinel squads can be mined and placed in one click and controlled with either the sentinel UI or the remote. This is great!

Thanks for the comments. I'll create a fix for the interaction with Fill4Me.
Regarding the follower count that must be an issue with the way the mod counts existing robots in the world as that is the number that is compared to the follower robot count. I'll see what I can do for this but my guess is this bug is caused by spawning/removing the robots in an unusual way.
I'm glad to hear it works nicely together with other mods. I might make a comment about it on the information page of the mod so other people can know about your finding as well!