I have a Land Pride ssqa hydraulic auger and recently finished re doing my fence. I noticed similar issues with auger speed and clearing out the holes.
The following worked best for me :
Dig 6" or so deeper than required.
Auger to full depth, stop the auger, remove from hole and spin off.
I do this 3 times and don't have to clam shell any dirt out by hand, and usually had to add a small amount of dirt and tamp while setting the post. My soil was pretty moist, but as a previous poster mentioned, adding water to the hole will help in clearing out the dirt.
It definitely doesn't clear the holes as easily as my old 3 point auger, but the ssqa hydraulic auger was soooooo much easier and faster overall.
In my case, I have a lot of broken up concrete in the soil about 18-24" down. A small chunk would stop the 3 point auger (either just spin on top or stall the tractor before I could clutch), requiring me to bust up the chunks with a digging bar and pull them out by hand. The hydraulic auger with down pressure brought it up nicely.