The accuracy requirement is different than reproducibility (precision). The accuracy of our pumps (measured flow rate vs. pump set point flow rate) is affected by check valve function, piston seal function, fluid viscosity, refill rate, system pressure, and other mechanical variables that impact performance.
It is fair to say our pumps have extremely high reproducibility, even at low flow rates. However, pump accuracy is more of a problem when the flow rate design levels are below optimal (under 1mL/min). A syringe-style pump might be a mechanically superior alternative for micro and nanofluidic rates.