Hi,
I am in the same boat really...The Saance stuff it's just useless, although cameras are not terrible. I would also like to replace the NVR for other better one which would have access via app, auto delete old, schedules, etc.
Main worry is the compatibility, I was looking at used IC Realtime units from Breeze HD range but off course there are other options. I want to keep POE so would not have to rewire again.