I have used the .40 cal 200 grain XTP on multiple deer, and my hunting buddies exclusively use the .45 cal XTP in both 240 grain and 250 grain. Between the 3 of us we've probably taken 75 - 80 deer in the past 10 years with these bullets (mostly with the .45 caliber versions).
Our experience has been that the XTP is a very good bullet for deer hunting, with maybe one exception. You need to be careful about how fast you push it - it sometimes has a tendency to come apart at high velocities. Generally when this has happened, the deer still dies quickly provided good shot placement, though. I don't think we've ever lost a deer due to bullet failure- we've only lost a handful of deer, and that was due to poor shot placement.
We've used powder charges in the 70 - 100 grain range with good results.