The previous Mendel X bracket was compact, but led the toothed belt along a tortuous path with tight radii and reverses of direction. I've had the X axis belt snap (which costs far too much!), after just 4 sets of Mendel parts, and others have told me the same. With this, the design is larger, but less prone to belt failure. We've printed about 8 Mendels with it now with no sign of belt wear.
The X-axis ground rods need to be shorter, at 463 mm long. Also the X axis spacers and two sets of bearings and associated fastners are no longer needed. The motor is attached by 4 shorter, M3 x 12, cap screws not on the original BOM. Finally, the belt needs to be attached inside out compared to before, and as such the motor direction needs to be reversed.
More details are here: