Agree. It's a thin line and skipping stops in larger remote cities would not be the first choice RENFE would take, but indeed; one or two fast EC a day might work, if marketing picks up, like for a scenic and fast Barcelona - Cáceres - Lisboa trip. But which agency would be best to initiate this?

Would that 6h30 include a stop into Mérida and reversing out again, or could skipping Mérida shave off an extra 10/15 mins?