Alright, I think I can see what's going on as far as Aya Hirano's voice acting now that I've seen it. It's the simple fact that she is overselling her lines at times like I've noticed she has a tendency too. This comes down to random noises, long holds on certain syllables and a whole lot of high pitched squealing at times that it's not absolutely necessary. She' s not atrociously bad, but at times it seems that while the other girls are focusing on their character, Aya Hirano is like a child in an amusement park herself with a "Hey look what I can do" attitude towards her roles. She seems like she's trying to improv, but lacks the self-control and ability to control pitch that other Seiyuu like Rie Kugimiya (Who actually did manage to make her way into this series as someone named Mio and I can't say I'm surprised as she's Rie Kugimiya and thus will be around in some capacity) have when they improv and thus her "moments" instead become rather shrieky and shrill instead of the moe moment I think she intended to create. If I were the director I'd probably want to take her aside and tell her that she needs to tone it down a little and that this IS in fact going live and to just follow the script a little more.
Anyway, the Absolutely Lovely Children theme was milked for all it was worth, much to my enjoyment actually. Seeing loli super robot wannabe's battle around is right up my alley and I kind of enjoyed their feelings smug superiority (the lolis do know they are at the top of power tiers in anime) modulated by some small idenification with their hapless overseer dude. Hopefully they don't decide to stray from their path and continue to be good little girls. We don't need a Midwich Cuckoos scenario.
And here is Rie Kugimiya's character if anyone is interested:
Final Boss? The character description on the homepage describes him as a teleporter and then proceeds to ask in a foreshadowing tone what his true colours are.