I thought long and hard, especially after reading and talking with Darell (of vvspy.com and swedespeed.com fame) about his experiences. Darell as installed every hitch available for V70's, although his is a T5 and not a XC.
You can read about his trials at: http://www.darelldd.com/volvo/tow_hitch.htm
I decided to go try the DrawTite because of the differences between the T5 and XC's height and bumper size. I was betting that it would fit better on an XC due to the hitch's lower stance and the XC's bumper hangs lower than the normal V70. The bet paid off! the DrawTite receiver fits just about flush below the bottom edge of the bumper.
I was concerned that the Da'Lan wouldn't hang low enough, and that the receiver would stick out the back to far. So far, the DrawTite is great -- of course I haven't pulled anything yet. I need to wire in the connector this weekend.
I'll get some pics to post as well. I didn't take any during the install because of all the grease and it was late when I finished. Actually, it was late when I started too. The install is very easy for the hitch itself. I did it solo, and it took less than an hour. It was basically taking out 4 existing bolts, fitting the hitch between the exhaust bracket and the car on one side and just holdingit up to the holes on the other.
If anyone in N. America's interested, I bought my hitch from http://www.hitch-web.com. Those guys are very knowledgeable, helpful, and quick to respond to email.