Never been a fan of these things myself. Aside from the aiming issues, they always seem to break right where the bit and shaft come together. My choice would be a nice sharp set of auger bits in various sizes. The torque of almost any size drill also seems to make the shaft torque and twist and misbehave in all kinds of directions. When the bit really starts to bite, that flexible shaft becomes the weak link unable to handle the torque required to drill deep holes
