I have upgraded a few bikes with Suntour Command shifters, and even did use a helicomatic 6-speed with the 7s shifter in indexing mode, since the Helicomatic freewheels have narrow cog spacing.
This was many years ago, and the old chains I was using allowed the occasional false-neutral effect just like when friction shifting with one of the Helicomatic freewheels and period Sedisport chain (what I was riding with today by the way).
With modern chain, either 8s or especially 9s varieties, many a mis-matched drivetrain can be made to shift unbelievably well, and I only wish that I had Shimano 9s chain available back when I was tinkering with Accushift equipment.


I wish I had a dollar for every time that I've needed to remind someone that expanding both sides of their frame at the dropouts at the same time is guaranteed to move the rear wheel off center. The chainstays must be bent and measured separately.
RJ bike guy gets a lot of hits but I sure wouldn't let that guy work on any bike that I cared about.
You can get a lot of profitable website hits just by breathing hard and pretending that you know what you are doing!