Most people seem to get similar. I don't have an XT, so I can't comment personally.
What I don't get is why they all seem to run so hot. They put out about 35-40W, 50-60 tops when vmodded, and a water loop should get you at least .2 C/W, maybe a tad more. In any case, its only logical that they should waaay cooler than CPU's, but the probe tells otherwise.
I didn't answer your question, but I'm also curious as to what sort of temps people are getting according to their probes. Air people usually get into the 60's, 70's or even 80's. That makes sense, but 50+ on water doesn't to me.