I would not hesitate to use FSUIPC.
MSFS relies on Windows for a so/so calibration of controllers, FSUIPC on the other hand, as you know, is quite good.
That in my books is reason enough.
There is so much more you can do to customize your controls with FSUIPC
Then there is MSFS itself.
I found, as did lots of others, that MSFS responds much better with FSUIPC7. Night and Day to me.
I also find it easier to set my deadzones and performance curves, although as you mention, MSFS is pretty good at that.
Do a search in here if you want more input. There are lots of posts on it.