It works very well with a FSQ106ED scope, and I have not had issues with swapping cameras at all (although the FSQ doesn’t really have a requirement for spacing). I do have flanges for both the FSQ106 and the TOA130, and can report that swapping flanges is actually fairly painless. Especially if you already know how many/which drawtube extenders you need for a given scope (my FSQ106 uses the 1" and .5", and the TOA uses the 1", 2" and .5").
Reducers do change the game, and you likely will need to use as few spacers as possible (again depending on your scope) my experience with the FSQ106 and the .73x Reducer QE is that I need to remove both drawtube extensions, remove the flange extender, and thread the WR35 to Tak72 adapter directly into the drawtube. This is likely an FSQ106 sspecific thing, as I know folks using the FSQ85 do not have this problem. Likewise, my TOA130 can usually come into focus fine without needing to remove too much.