If you can live with the form-factor and can wait a bit, the SG9663DC might be a better option. Pros: Should be a better design and overcome any previous problems, should be better vid quality, and should end up with better large card support than the RC. Cons: It's a new cam and other than the vid quality none of this has yet been solidly proven.
You can see what people have experienced with the SGZC12RC in it's forum here on DCT; it is not without some issues though you can say that about most dashcams. I decided to wait on the new cam, you decide for yourself

The SG team is one of the best and IMHO either will be a good choice. Here it is just comparing the known to the unknown with what I believe are better possibilities for the latter

If you want a proven winner there's none better than the SG9665GC but it's not a 2ch cam.
You pays your money and you takes your choice. Do your research well and you'll make better choices

Phil