Consistency is the name of the game when sharpening or touching up ANY loop and why I prefer an indexable grinder where the loop is secured in a vise arrangement off the saw and the machine holds a consistent grind depth, tooth profile and raker height on EVERY cutter on the entire loop which is almost impossible with hand filing because of the human factor. Humans wiggle, machines don't usually.
Why machine tools were developed initially. Machines provide consistent and repeatable accuracy that hand dressing can never duplicate.
I would never purchase a hand held sharpening machine like that, no matter what the price point was because of the human wiggle factor.
Of course the built in rigidity of any grinder is paramount so the cheap plastic grinders like the Harbor Freight one, flex under pressure whereas a metal one with aluminum die castings don't, plus the grind angles and depth settings are accurately repeatable.
Cutting loops are all about consistent accuracy to provide a straight and aggressive cut and it's almost impossible to achieve that with the human wiggle factor included. Why, when I'm cutting wood, I always carry an extra sharpened loop with me, just in case I somehow fock up the one on the saw.