Aye I think Vect using the regular archon rules should work fine honestly at this scale and abstraction. I'm not sure if my skills are up to sculpting his erm, entourage, yet.
Yeah the next sculpting is a hard one.
-Reavers are the fastest unit in EA I think, but hoverbikes arent that unique, you could arguably use one of the existing eldar bikes in dark colours and be happy so I'm not really filling a huge gap.
-Hellions have hoverboards! also I probably also only need to sculpt the board and weapon and then just use the wych bodyparts for them, so relatively quick job though not sure jet how to make them strong enough. You'll notice all the warriors here have a loincloth or other third point of contact to make them less brittle.
-Scourges. Wings sound both exiting and challenging to do right, but I could probably again re-use warrior and wych bodies, sculpt a couple bird like helmets for them. Posing again a challenge though I think just doing flying stands on them can be forgiven there?
And yes haemonculae. The surgeons from hell are going to be fun, they haven't changed much between editions so I'm good there. their creatons though. the AE list uses Grotesques, which used to look like this:

but the name grotesque is now used for these:

with a new unit called wracks introduced that are closer to the old grotesques

Stat wise we are looking at this:

descent save, great close combat no ranged capacity whatsoever, and fearless so no impression on them. (not that it would matter most of the time, they have no ranged weapon so get skipped)
I'm not tied to the old sculpts, they don't read well at 28mm and at 6mm would be pretty unrecognizable. There isn't a lot there to work with for me. The new wracks are much more interesting but again, at 6mm they might end up looking very close to the haemonculi themselves which they are mixed in with, and I'd like to provide some good table top recognizability here. I might do something closer to the new grotesques, hulking stooped shapes with big blades and claws, seems fitting, maybe a bit smaller or only 3 to a base? I'm not sold on that yet.
In the same manner, I noticed that the new 28mm wracks actually come with parts to crew a raider with them. I love that idea, if I actually make it that far I would like to do that, but not sure if that would work with the big guys... Both is an obvious option but that's doubling my work for not that much payoff game wise. So undecided. I could ofcourse also just try to make my own interpretation of the concept, see if something pops into my head before I get to them.
Also worth noting that the new wracks in basic, topless with skirts, armed with hooks and choppers is very close to the new look of mandrakes. the old mandrakes were pretty much just male wyches so I'd prefer to use the newer look (though maybe offering 2optiosn with pistol and magic blasts both?) but that pretty much reserves that overall profile of look for them.
Talos is absolutely a go, I'd like to try for the styling of the new one, with rounded armor etc but the overall posture of the old one, more scorpion-like. I have to say though vanguard miniatures proxy model for it is fantastic looking.