>>>>It's actually a misconception that Spanish horses have roman noses. The roman nose is a draft horse trait, traditionally, Spanish horses had a subconvex profile, similar to the roman nose but not as extreme. The extreme roman nose on modern spanish horses is similar to the extreme low hip in German Shepherds overbreeding of one characteristic that leads to an extreme or over-exaggeration. Luckily, there aren't any negative aspects to a roman nose like the GSDs.
It must depend on which definitions of "roman nose" and "subconvex" are being used. I have found differing definitions even among Spanish horse breeders and associations-- including one on a Lusitano site which says "the Lusitano horses possess a sub-convex contour which is also referred to as the ‘roman nose’" , and another describing Sorraias that says Sorraias have a subconvex profile, and that subconvex means 'Roman HEADED' (convexly arched from poll to end of nose) vs. Roman NOSED (described as having a flat forehead, with a convexly arched nose below the forehead.)