When I tried to do this to one of my 3MP Bullet cameras (DS-2CD2032-I), for some reason it changed the model number of the camera completely and wouldn't let me connect to it. (SADP gave me some random numbers after the 'DS-2CD' part of the model) I had to perform TFTP recovery to start from square 1 again. Before having it fail in this manner, I repeatedly got a message via telnet telling me that there was no room for storage on the device. No matter what I tried, it would not let me move the davinci file back onto the camera. So for the time being, I have given up and stuck with 5.1 which honestly works fine for my needs. It would have been nice to bring it up to the latest firmware though.
If anyone could offer any tips on what I might be doing wrong, that would be wonderful. I've followed everything step by step (both easy and hard ways) to no avail. Considering that I do actually have some genuine US version devices, would it work to pull the davinci file from one of those and then place it onto the CN version devices? Just a thought.
PS. Hikvision just released 5.1.4 beta a day or so ago (6/10/2014), and can confirm it has the same effects as 5.1.2; all Chinese, and no web update allowed (TFTP only) when using non-US region devices. My 3 genuine US version devices accepted it with ease and all seems to be well. I really don't know what they changed in 5.1.4, but performance seems fine. Nothing out of the ordinary.