I'm sure you are talking about meteorite men..........
the guy that broke his was riding an ATV and snapped the rod the holds the display on. if he had been carrying it properly he likely would have never broken it. I've only heard of two breaking like that, and both were due to rough handling.
I have an origonal F75 thats never been back for anything....with hundreds of hours on it, and let me tell you....its been USED! thats not to say that things dont break sometimes, or a particular part may not be made right on occasion, but overall, my Fishers have held up every bit as good as any machine I have even owned....and I've owned a few.
Some guys complain about the quality just because of the way they feel (light and easy to swing), even though they have never had a failure. If you take care of your machine (barring accidents), your Fisher should provide you with years of service. I've honestly had more failures over the years with one particular top brand that I have owned a number of (that has the reputation of being heavy and built like a tank) than I have had with Fishers.
I honesty wouldnt worry too much about the "build quality". The few small issues Ft had when they first released to F75 have been resolved (like the hand grip splitting on some machines) . Go ahead and take the leap. I think you'll be very pleased.
One other little thing. I dont know where you heard the F75 is 50% deeper than the MXT, but I dont think thats quite true. While I think it IS deeper.......................... but 50% deeper may be a bit of a stretch. (I have both)
Both machines have their strengths and such, but believe it or not.....both had the same lead designer!
The f75's biggest advantage is its ability to see things in heavy trash and iron that the MXT cant, do to its superior coil design and super fast recovery. Thats not to mention its better ergonomics, and the fantastic battery life. The F75 will run app 80 hours on the same batteries that that MXT will go through in 16 or so. Thats a big difference!
You have a good machine with the MXT, but in my opinion, the F75 is far better....