I finally got to use the toothy side of the tooth bar this Memorial weekend, yikes!
Digging out a dirt/rock/debris pile from some other landscaper ("do it cheap" sure leaves a mess for the next property owner...) the Piranha Bar cut through it no problem, way better than the OEM bucket edge. The teeth hit large rocks (at slow speed) with no damage--in fact the toothy side is great for digging out rocks, rotty stumps, severing roots, spearing chickens--no no, not that. The Piranha Bar really does work great, especially in the mess that included buried conduit, drywall corners, rebar, trailer parts, etc. Note I did not abuse the Piranha Bar, rather I slowly and carefully pried out "stuff" from the mound, sorted it into piles, and did the job cautiously.
The name "Piranha" certainly fits, and for me it definitely seems worth the investment.