Let me clear things up. FXR's are not Dyna's. The frames are different. The rubber mount system is different, the tranny case is different, the swingarm is different, the primary's are different, they ride different, handle different, look and feel different. FXR and FXD that's different.
Eric Buell helped refine the design of the FXR. If you notice he used the same rubber mount system on all Buells up thru the late 00's. The frame is torsionally stronger than Dynas, it has a shorter primary, and takes horsepower well. I could go on and on about the differences but it'd bore you.
I am biased I admit. However. I don't call your Dog a Cat.....they are different.