As Uma said... I test rode one and a vrod.
http://www.twowheelfix.com/showthread.php?t=14236
I'm probably one of the biggest pro HD guys here. I love HD's but I can agree with you on the XR. I was expecting more out of it. A buell motor even out of the XB would be a better way of going. I didn't like how it felt top hvy like a dirt bike.
The crazy part is that the nightster feels faster than the XR. Considerably. I'm not sure about the exact differences between the motors/heads. Further, I even rode the nightster to my demo ride... so it was easy to make this comparison.
If I could buy any HD right now, it would be a nightrod. HANDS DOWN. May not be what you're looking for, so sorry it's no help.