We had similar thoughts. I was also impressed with how the 1F Z assembly design keeps the cutting centre close to the X axis rails. With the new X50 rails, I do not think adding a new (better/more flexible?) Z axis system that pushes the centre out 1-2cm more would be as much of a concern. I also consider buying and using a second 80mm mount. Right now the linear bearings being used are 70mm long, and the 80mm mount is 51mm high. If four new linear bearings are purchased that are 50mm long, then the overall double mount would be 102mm. The minimum amount of Z travel we would then loose would be 102mm - 70mm or ~ 30mm.