Actually, I've been more interested in the FX4CR for a long time.
The FX4CR has been continuously upgrading and replacing models (found an error -> Software and hardware upgrades -> (Found an error), I changed it after about six months because I felt the hardware wasn't stable enough. It always looked like a work machine. The after-sales service in overseas is good (you can return if you don't like it, and if there are hardware problems, they will send you a new module). I'm not sure about the domestic service.
The 6100 has a different appearance than the FX4CR; it's not as refined or compact.
I'd prefer to wait and see how the FX4CR performs after the release of the 6200. If the 6200 is stable, I'll stick with FX; otherwise, I'll use the 6200. As for the FX/6100/6200 combination, I lean towards using the FT891.