There has only been one Flexit sidecar l'm aware of here in Oz, and that was here in Melbourne and fitted to Peter H's ST1100. I followed it on a few occasions and the bike rode very well.
It didn't have a leading link, but cannot remember if Pete had to altered the rake angle at all. Anyway l haven't seen either Pete or the bike for many years. But he'd done a grand job of fitting it...had a matching wineberry colour so it was quite distinctive.
I don't think Flexit made many RHD 'chairs', so l'd imagine it's both rare and collectable now.
Cheers the can :-)