Besides what was mentioned it's worth considering the following...

A rock climbing harness is designed to catch you when you fall on a dynamic rope. A tree climbing harness is a "work positioning" harness designed to support your weight on a static or semi-static rope throughout the entire climb. A huge difference. I can't stand to hang in a rock harness for more than 5 minutes. Any tree climb under two hours means you were barely in the tree. A typical tree climb where you set the rope from scratch is going to be at least 3 hours.
-moss