I will chime-in here, since I used a similar method for a long time. I had no clock signal for many months a couple of years ago, and my clock did not noticeably drift. (maybe seconds, but not minutes) But my DHG never ran for more than a week without a crash or automatic reboot. Since the clock can only be frozen (not pushed forward), each reset made the clock move backward through the calendar week. Also, since I usually record every day, I would rarely wait long enough to get the correct time on the clock. Instead, I'd settle for 12 hours off, or less if I wanted to record something sooner. I kept a note to remind me how many hours it was offset until the next reboot. When I finally rolled back to the correct weekday and time, it was cause for celebration -- though short-lived.
Having the calendar offset makes it cumbersome to record programs that are on M-F, but most of what I watch are one-off movies.