Sorry for bumping a week old thread, but I registered just to reply to this since it seems there's still a bit of confusion.
For background I'm a dual HK/Canada national who was born in mainland China. I flew SFO to PVG via YVR on Air Canada in 2016 and this was my experience:
1. SFO check in: machine initially wouldn't print my boarding pass due to not having a Chinese visa, but after some finagling I somehow got it to print
2. Got paged at the gate to verify documents; showed gate agent my first gen HRP (non-biometric, no English) and there were no further questions
3. On arrival at PVG, used Chinese citizen's line and showed HRP; was asked which flight I arrived on but DID NOT need to show any passport
4. Hotel registration, train ticket purchasing and all other activities of the sort were easily handled with my HRP (hotel registration additionally required HKID)
5. Flying out from PVG, showed Chinese exit immigration my HRP but was asked for a passport. Showed my Canadian passport and lady was completely unfazed. Proceeded to stamp my boarding pass and cleared me in under 30 seconds. (my HK passport had expired for 2 years already, besides I didn't have a US visa anyway so it wouldn't have done me any good)
6. On arrival at YVR, went through CBP pre-clearance with Canadian passport. CBP agent asked if I was a dual national since I didn't have any Chinese visa or entry/exit stamps, answered yes and that was it.
I too was super anxious at the time since there were so many inconsistent stories on the web. But having gone through this once myself (with an expired HK passport no less), operationally it really is quite simple and there's no need to be nervous. My mom who does an annual YYZ to PVG trip once even got an inexperienced/trainee exit immigration agent at PVG who apparently had never seen an HRP before who asked her "what's this??" A senior officer immediately stepped in and told him "she's a Hong Konger, just let her go" and that was that.