I would change the Roach model into SC2 Roaches and not Primal Roaches. I like SC2 Roaches way more and they feel a lot more Zergy, but that is just my opinion.
If they want to make the Roach distinctive to prevent it being confused with the standard SC 2 Roach, they could use the Vile Strain model from the campaign.
Yeah, that too.
To be honest, all three of them look a lot better than Primal Roach.
Just the normal Roach is fine with me. The evolved ones look a bit silly with over the top colors (bright Green, Purple). Though if we cannot pick the default Roach (don't know why not) I'd also favor Vile Strain over Primal.