I've got a shadow XT and got it when it first came out. It required very little adjustment out of the box, worked great with the 8 speed setup I was using, and of course worked even better when I went 9 speed. I've given it a pretty hard work out and it looks brand new other than the usual dirt.
I've never used XTR, but I feel no need to upgrade at this point. I LOVE the shadow xt that I have. i'd get the shadow version personally.
Of course as was said the new saint is a kick ass RD. If you're going to beat the ever loving crap out of your rig then you'd be better with the new saint. So your choice, I think, is between the saint, and the xt shadow RDs at this point.