No, but I've used quite a few of Canon's full frame bodies.
Fujifilm's IQ is top notch. Their APS-C sensors go head to head with full frame and win. I love the build quality, image quality, weather sealing, lens selection, ergonomics, everything. The only disappointing aspect is battery life, but the X-H1 comes with 3 batteries so I can't complain too much.
As others have said, Fuji focusing on APS-C and medium format is great. APS-C is a very capable sensor size, yet every other company uses it to incentivize an upgrade to their full frame system. Not Fujifilm. You get a no-compromise APS-C platform that destroys full frame cameras that are twice the price. If you really feel the need for a larger sensor, you can get medium format, which is way larger than full frame, for a similar price.
Hope this helps :)