I have a client that wanted look back five months to check something on her camera system. I told her that's probably to long, after checking, I was able to go back three and a half months.
She flipped out and said her other two houses can go back two years. I felt like saying show me some footage from two years ago!
How far back have you seen an "average" DVR history or even a "high end" unit go back? I know it basically depends on the hard drive size and video quality. But even with crap video quality and 14 cameras it'd take a hell of a lot of hard drive space to keep two years locally.