I've heard both the Mofi 888 and the Fyne 501sp, unfortunately in different rooms/systems but still.
From what I could tell they were very different to the point where each would appeal to different types of users, and each would work better in different systems.
The Mofi was more dynamic and I'd say technically correct? Great detail, nice imaging, very clean and well rounded. For me this would be a better speaker when playing complex big band or orchestral works, technical metal, and even just loud rock in general where I want it to be punchy.
The Fyne Audio speakers struck me as being more "pretty" sounding, kind of like certain older Sonus Faber designs. So not ideal for really technical and complex music but fantastic with small scale jazz and classical, or singer with guitar type material. There's a certain romantic coloration to that music which is more emotionally involving than the Mofi.
Obviously this is based on the systems and rooms I heard them in so it isn't definitive by any means. Both good speakers but extremely different, you really want to try them for yourself if at all possible.