I would never recommend anyone back down a hill with a load, most people have a hard enough time backing up, get a load pushing you drop a tire in a hole or hit a rock, or the front end starts to come around. Just gear down start down with the load low and be ready to put your bucket down into the dirt if need be, you are much more in control driving forward then backing up. And if it gets out of control backing you have lost it, forward you may ride it out.
You do what you want but the proper procedure is to keep the load on the upside of the hill! the tractor is more stable and the weight on the front isn't overloading the front axel when doing it proper. If your still not able to control it due to wet slippy/muddy ground then you already did something else wrong like didn't chain up or went down a hill you shouldn't have to begin with.
I have fired operators who thought they knew better after they destroyed things and cost me money but the funny thing is those who listened and did it the right way never cost me a cent.