I did leave that possibility open. The center extruder mount can be made taller, easily in my CAD and mounting to the ends just requires longer screws.
I did see that printer and wonder why they would mount the rail in that orientation. I chose the weak direction to only have to support the extruder weight, not the insane accelerations. The other thing about that one that strikes me a bit odd is those idlers screws not being supported. Has anyone looked to see if they flex under high loads? The tiniest of supports will easily make those screws 4x more rigid, and there is plenty of room to add a strap from the tops on all of them. Other than that, that printer is seeeeexy!