I would imagine that there would be very little if any difference with the 1.0l EcoBoost engine across the range, and indeed a re-map would be possible.
Warranty-wise, wouldn't it be possible to have a Ford garage, or Ford's performance partner - Mountune - undertake said re-map without voiding.
Also, if a re-map is possible, then Pumaspeed do a 150ps (and upwards)upgrade for a 'Fiesta' EcoBoost' - albeit they may react interestingly in response to a request for a B-Max application.