Hello David
Well I own neither but have been very impressed with both. I would have no hesitation in selecting the Small Seconds because it's more subtle but no less classy in every way. The X2 is for me a big improvement on the size front having owned a Byzantium before. I prefer its' larger size to its' slightly older sibling. The X2 is an impressive watch but I wonder if the Prestige Small Seconds, because it bears more of a classic and subtle appearance will be more enduring in its' appeal.
The winding action of the crown of the Small Seconds is so smooth it defies belief. I do wish it takes the strap with the deployment clasp though. I expect because of its' more classic style, Omega had chosen to accord it with a tang and buckle instead.
Hope this helps in some small way.
Best WIShes
Houston