Mechanical preparation is superior to acid etching for many reasons. Mechanical preparation does a much more thorough job in removing bond inhibitors like paint and giving you a proper profile for the epoxy to bond to.

Acid only reacts to concrete. If there is paint, drywall mud, oil, etc on the concrete it will not penetrate through that, which leaves that area not prepared to receive the epoxy coating.

These products are commercial grade. Mechanically preparing your concrete will give you a long lasting, professional installation.