I also doubt we'd see a .45 Shield. It's much easier to 'design down' from a .45 to smaller calibers than it is to design up from 9/40 to a 45. Of course... If the XD-S becomes Really popular, S&W could surprise us and come out with a .45 Shield. With all the initial issues I've read about over on the XD-Talk forum, it may be a while before the XD-S really gains momentum.

In shooting the XD-S side by side with my old PF-9 , G26 and Shield, I'd consider the XD-S's recoil to be similar in feel to the recoil of a PF-9/LC9 (rather rough, but not bad at all for a subcompact 45) and the recoil of the Shield to be closer to that of the G-26.

While I enjoy shooting my Shield all range session long, as Hohopelli wrote, I'd never consider an XD-S as a 'Shoot for Fun' kinda pistol... More of a 'Shoot enough to keep up proficiency and put it away' kinda pistol, like my PF-9 was.