Hi MD - I don't think extra bearings will help much but the gantry seems small for machining work? Will be fine for plasma....The thing with square rail is that they are stiff in all directions so what happens is the bearing closest to the load does most of the work so the bottom ones on the Z axis for instance wear before the top ones do etc. With pull downs it's often good to rotate bearings to even the wear. Some people like this idea some don't. The columns are solid especially with the transverse beam (saddle) underneath but then as you say the machine deck has to be stiff as it doesn't have a frame under it....Peter