great question Ninja. will definitely save you from wasting money before taking the plunge with either. I've found that dongguan services vary a lot among providers. more often than not, it can be a glorified extra shot (which normally costs $80 as an upgrade). i've experienced true dongguan in china and I have yet to find anything comparable locally (which is why it's been a long time since i've opted for DG upgrade). in China, it's an entensive service with hot and cold effects during foreplay and full body teasing, etc. there are probably a lot of other members on PERB that can provide helpful insight.
There is a Chinese movie “Due West: Our Sex Journey” and there was this scene towards the end, that is real Dongguan. Check it out, you can’t get it here, the service is based on the name of a city in china. It’s a next level of service than Nuru, Although both share some similarities. It’s invented to serve the most powerful politicians in China