Thanks bernard_L, as Prof_Pixel points out, the condenser / tungsten curves look reasonable when you align the curves by the mid tone. I downloaded the tech sheet from the Ilford web site for MGIV RC and it contains a similar plot, showing that my results are quite similar to the tests done by Ilford. So I am satisfied that my measurements and values I obtain are reasonable.
The Diffusion / LED source has me interested. There is a more pronounced "kink" in these curves that leads me to believe that I am getting a substantially different contrast for the shadows than I am for the highlights. I need to absorb your comments a bit more, but I was starting to look at the spectrum of the LED vs a tungsten source to see if this could explain the difference. A tungsten curve is fairly constant in the 400-600nm wavelength as opposed to the LED that has some sharp peak's and valley's. Could some of the "missing" wavelengths cause this? Maybe I guess I would need to compare the spectrum to the pass wavelengths of the filters. I am also going to generate curves for non-VC grade 2 & 3 papers using the diffusion/LED head and condenser / tungsten head. My guess is that they will look a lot more similar to one another.