I've used the µ4/3 Samyang and I liked it. The problem with a fish is you need to be creative in order to use it effectively. And being creative is a lot of work. I think I'd just rather just look at you being creative and me enjoying not having to sweat.
What, you don't have a creative button on your Fuji? Mind creates out of focus images, converts them to contrasty B&W, adds grain and a vignette and calls the results artistic expression. Hit the button twice and it does all that with a dash of sepia.
From my past experience with various fisheyes, no correction results in a perfect shot. It is cool to play with, you can get some crazy effects but you will probably not come out with anything looking like a normal image. The last image I posted was originally shot with the horizon directly in the middle of the frame (keeping it straight), then ratio cropped to move the horizon down a bit. It was not corrected at all for distortion.