Although I cussed it at first, the elcheapo Lienbach (sp?) 7400 I have has proven to be pretty darn tough. With just a little bump in the injector pump (shhh!) I am putting out right at 50 PTO hp. I would break both of the grade 2 shear bolts on about every hole. That sucked! I spent a hundred bucks and bought a slip clutch for the PTO drive on my PHD. That worked a little better, but I still broke the grade 2 shear bolts very frequently.
I didn't have the time nor patience for that deal, so I went with grade 5 shear bolts.
Since then I have drilled about 3000 or 4000 holes. I broke 2 sets of the grade 5 bolts and twisted one 12" auger in half. I bought a higher quality auger and have been drilling away. My Lienbach 7400 PHD including a 12" auger was under $400 including tax and all. I'd have to say that I'd do it again. I really don't need the PHD anymore, so it just sits around. Wanna bargain on one?