It may be just a single Variant per Model, otherwise HBS could have taken the total of 470-tons of new Mechs to a greater total than just 470.
Plus, these seem to be the only Mechs we see in the now three HEAVY METAL videos provided by HBS:
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That is such a beautiful picture. Warhammers, Riflemans and Marauders oh my. But given there is no Rifleman-5D, that will make building that thing up a little more interesting. I find trying to slap 2 ACs in that thing's arms, alongside Lasers is rough. Nevermind striking a good balance of armor.
The Annihilator will be fun times. Big ol pot bellied, giraffe necked derp gun mech.