That probably won't make a difference. I don't have any personal experience with a cable card in the DHG, but getting that error on a "real" channel is very strange. Since you have a lineup that comes from the cable card, you need to decide if moving down to 1.2.13 is worth the risk. There is no way for me to test it, sorry.
I use a cableCard, and I just loaded 1.2.13 a few minutes ago. It works fine so far. My "unknown" recordings lost their titles, but no big loss there. I scheduled dummy test recordings on a few channels, and none of them produced the "not in lineup" error, but that is usually the case after a reset anyway. I need to wait and see if I am rid of it the error for good. I will reset to midnight with 147412356 at 10 PM tonight, then unplug tomorrow and drag the clock back to the correct time (rather than stay up until midnight). I'll be out of town after that until Sunday, so it will be a while before I see how stable the new set-up is.