I just wanted to post an update about these babies!
Three of them wound up being some manner of Heirodula sp: two females, one male. I kept the male, and released the other two girls, since they all appear to be the very same species as my other girls (despite looking very different as L1/L2 nymphs o__o)
One of them, however, turned out to be a completely different genus!
Behold, Noi the Rhombodera:
As you can see, she's a subadult now. She's also as big as my largest (adult) Hierodula. She's really trigger happy with threat displaying--but she's all bark, no bite.
Her shield, while definitely very different from my Heirodula girls (broader at the top, with a more gradual tapering towards the base), is pretty humble as far as a "shield mantis'" shield goes.... There's apparently a species called R. longa which fits the bill for this girl, to a T. So that's been my casual ID for her.
She's really cool! Her pink chest is very charming. I wished I had a male for her, as well! (why are the boys so difficult to come by, in the wild!?)