No one has spent the time to come up with a test setup. Minimum Discernable Signal, Saturation Signal, Garble Sensitivity, and DME suppression bandwidth.
I suspect they both use the same Analog Devices receiver chip, the same filter width, so the test would have to determine which one handles garble better, or is more resistant to interferrence.
Barring that test, the customer would probably choose which device they wanted, by looking at the software package that displays the result.
Some people need a lot of eye candy, others like to see a lot less. Myself, if I like a black screen, green tracks, and a couple VOR's to orient myself :-)