I have found if you want things to remain frozen for a few days then around -2 will do it providing they were rock solid when they went in there.
But they are really efficient as a fridge at around 1-2 degrees. As soon as you drop to zero or below they cycle ALOT more to keep it maintained when in the same ambient temp as keeping them at 2 degrees. Just my findings of course.
I have gone away for a few days and took plenty of frozen meat and had the fridge on 2 degrees and it hasnt even cycled on for a couple of days! Just the frozen meat was enough to maintain the temp. Mind you this was in Tassie.