I guess hybrid SM dolls aren't that uncommon, as SM have been producing silicone heads for a while.
This lady here is a SM-DS Hybrid (SM170C Pink Body + DS "nanase" Cream Head).
As her head is from a different manufacturer, there is noticeable colour mismatch. But it's a difference I can live with. Proportion wise I find the "nanase" head fits reasonably well with the Sm170C body.
I got the adapter from a vendor from the chinese site Taobao. Probably hybrid DS-m16 dolls are common there too.
Even though it's been a year+ since the SM170C was introduced, I still find her to have one of the most realistic and attractive curvy figure around.
Here's some pictures of her
Daylight
Nightime