H264+ is a Hik-only (I believe) encoding scheme to reduce bandwidth and storage size. Based on their white paper, they're ignoring small changes in the background image and doing predictive analysis and active adjustment of bit rate requirements vs long term time frames. Sounds like there's some risk of missing small details and a need for "slight adjustments on the play strategy to improve the playback experience".
I'd avoid it unless you need bandwidth/storage reduction and want to be one of the guinea pigs!
Here's what their marketing people say about it:
The popularity of the high-definition video and the growing bitrate caused by the high resolution can have quite some impact on the network infrastructure and storage capacity. H.264+ technology is a kind of intelligent algorithm developed by Hikvision. It is a remarkable encoding technology which focuses on the features of the surveillance video and is optimized based on the H.264/AVC. H.264+ decreases the bitrate of the surveillance video greatly so as to save the system cost.
They've got a more detailed white paper here:
http://www.hikvision.com/europe/uploadfile/WPHikvisionH264V10.pdf
