Even if that was 2% absolute accuracy and not relative, we were seeing a 10% absolute difference from what the purple pro read vs what our state licensed compliance labs were testing at and I trust the lab we work with quite a bit (their potency values fall in line with our estimated extraction efficiency and output from distillation - all within a few percentage points of error of course).
It’s just not a piece of equipment I would ever want to recommend to put any stock in its output from my own personal experience.