I think we took around 4.5 hours to get up to the peak. It was a good mix of sun, rain and mist. View was really magnificent! Our guide, Will Ho from RoundTaiwanRound really took great care of us and even treated us to hot coffee / tea as we gaze at the view from the cave. It was a wonderful experience never to be forgotten.
You need to get a mountain permit before you can attempt this trek. One of the members of the group needs to be a Taiwanese as well. It feels great when on lookers could only see from afar and look at us enviously as we were allowed into the forbidden area after we showed the guard on duty our pass.
I would strongly recommend Will as your guide!