I don't have the FW but I do have an early version FX which shares a lot of the FW parts. Mine is the brown cowhide version they first came out with and I bought it new about 10 years ago or so. I have traveled with mine to Mexico and on hiking trips and to the coast numerous times. I am not sure that qualifies as heavy use. I also have a 2.8F in the last version made in the early 1970s that has been maintained by Harry Fleenor for comparison. In most ways my FX still feels like a new camera. The transport is effortless as is the focus. They are both better and smoother than my F. I have only had two durability issues with FX. One the brown cowhide is not as durable as the older leatherette on my F. Not that it is disintegrating or anything but the brown finish has worn off a bit from my handling. Also my FX version has the chrome edges on the back door and the extreme shininess has dulled a bit though it still looks good. The other durability issue was with the metal name ring around the planar lens.. the one that says Planar HFT. With the older F camera that ring is screwed on but with the FX it is glued in place. Mine must have been too lightly glued because when I returned from a trip with it the ring was gone. I had to buy another one from F&H in Germany and glue it on. No problem with that since. I don't use the meter and so don't keep a battery in mine.
I do like the newer version black leather without the chrome edges much better. I just like that all black look. Just cosmetic. I also like the fact that my lens is called a Planar instead of what they call it now.. which is S Apogon, though it is the same lens.