It's not a substitution for an actual sync on a running motor. I'd venture to say, it's another option, and maybe better than a feeler guage or eyeballing it.
I'll check it at some point. Valves are in spec, carbs are clean, main jet is too small. It idles great. low throttle steady state hunt and surging is gone, but it's lean up top. Main jets will be here tomorrow.
I'd venture to say, it's closer than bench syncing with a feeler guage or eyeballing it. As well as it's doing right now sync is lower on the list than getting WFO throttle working right first.