I had a 3 point auger for a while It was absolutely useless here on my Tennessee property nothing but clay and rocks here sold I sold it less than 1 year old.
Very nice! Congratulations. I usually don't hit clay like that on my property enough to justify the extra cost over a 3-point digger. Mine tends to be wetter, or as we call it, gumbo clay. It is sticky, but not so hard unless it is dry. Still fairly easy to dig as it is usually topped with enough sandy topsoil to keep from crusting over in all but the driest conditions. But if I had to drill a lot of holes in your hard clay, I think I would definitely have to consider getting one.