I did not know that about the MDX. I'm suprised that Acura would make a fixed rack, given that there are people out there, like us, who load all kinds of things on the roof of their vehicles. This non-adjustable rack would also pose a challenge to mounting our Thule Roof Box Carrier on an MDX as well, since it requires a precise spread between the crossbars. Frustrating.
Nonetheless, it looks like a Yakima or Thule solution is best for you, with more strength and versatilty than either of the factory racks likely have.
Rob