So more to the mystery. I can't find a pic too quick. All fiesta ST agents have the recaros. A bit of searching could find one but here's a video posted on this forum.The STs that were in the EcoBoost challenge all had low-profile headrests. I figure that's about as close to production as we'll see before they actually arrive in showrooms. You mentioned Movement members with larger headrests, were they the Recaro seats or the standard ST seats? I have't seen a picture if you could link one?
There are a few shots if the back seat. Try not to get caught up on the model