That sounds like a cool project! I'm very much looking forward to it.
Re: Goliaths tactical role, resistance mechanics, backing it up with supports, etc:
I should confess up front that I probably have an aesthetic preference coloring my assessment of the tactical balance.
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I said that goliaths felt weaker than other NPC classes, to me, and they did feel that way -- but unconsciously, I probably feel they ought to be *more* powerful, or at least have more of their power indexed into durability. It just feels strange to me when a towering size 3 mech gets bursted down immediately, even if that Size 3 mech didn't represent a greater investment of the notional "encounter design budget" or "army points limit" for the NPC side than a random size 1 Sentinel ... okay, rebaked Sentinels are size 2, I guess all the defenders are size 2 now. But still, it just feels like a size 3 defender should be more durable than a size 2 defender.
If the classes are meant to be balanced against each other, though, it's probably actually correct for a Goliath to be easier to kill than most of those other defenders because it's so outrageously good at gumming up the middle of the map and preventing the PCs from going where they want to go.
The first time I busted out the goliaths, the PCs were on a mission all about assassinating an Elite Commander Veteran Witch who hid way in the back behind a stack of Goliaths who kept diving in suicidally to keep the PCs away from her, and it actually played just fine as a tactical combat, I just found it comical to watch them blowing away so many big boys so fast.
(Also my PC team had both a 3-tac-knife-hunter-nelson and a Centimane-Autostab-Gunslinger-Scylla Gorgon, so they were extremely good at deleting big piles of HP as long as armor = 0)
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That said, it's a little counter-intuitive to me to be throwing support on a defender like the Goliath; at least, it feels like double-counting in a sense. I actually put the goliath in my Greek-themed "monsters and witchcraft" army which was built around scourers, rainmakers, and specters for dps, mirages, priests, and hives for support/control, and demolishers for point defense. The way I see it, a Goliath is supposed to be there to protect my Scourer, but the Priest is also there to protect my Scourer. If I'm having the Priest shield the Goliath, I've now committed 2 units toward giving the Scourer the same amount of indirect defense 1 Goliath already gives (only the Goliath doesn't die as fast), and it's not clear that I wouldn't do better to just have my priest shield my scourer. (Scourers in particular are a good case for that because unlike the new Goliath, they DO have both armor and damage resistance, so they can stretch that Overshield MUCH further)