I recently got back from a 9 month exchange in Hong Kong and I wore the kilt exactly twice: once to an international event organized by the university and once to a Burns Night.

I also had the opportunity to travel to Guangzhou in the mainland and to Taichung in Taiwan. There seem to be fewer foreigners there than in HK and many people were openly staring at me, especially in mainland China. Personally, I didn't want to do anything to make myself stand out anymore than I already did, so I didn't wear my kilt much.

That being said, you should be OK and I know other Xmarkers have worn kilts in China. I would advise you to wear underwear but not a sgian dubh, just in case either of those things should somehow get you unwanted attention from the police.

I would also advise you to start learning Mandarin, if you haven't already. Kilt is:
苏格兰式短裙 [Pronounce] sūgélánshìduǎnqún, which means "Scottish-style short skirt."