The thing is, the majority of Aurvandil doesn't use SF because of that awesome inf center. Are their any advantages of an equal CS SF unit Vs. an inf unit?
No there's nothing
actually though, SF units each have their own secret ability (some of the time? all the time? not sure)
for example there's a ranged SF centre in Talerium in Atamara that is equivalent to an archery unit while ranged and an infantry unit in hand to hand, but if they fire from 1 line away they routinely do 1000+ hits. absolutely incredible early in battle, i roleplay that as hurling greek fire/wildfire if you're a game of thrones fan. problem is you have to experiment to find out what their ability is, i'm waiting to see a cavalryesque SF centre and to shake in fear at the hits they land.