If Cobra is correct in his summation, I have a few problems and suggestions.
1. It would seem to me that NEXRAD should be NEXRAD. If iFly is converting the NEXRAD intensities to the equivalent ADSB intensities, I would request they cease that practice, or change "NEXRAD" in the documation to something like "Simulated ADSB WX RADAR". If I think I'm looking at NEXRAD, I'd like to think that wherever I look (TWC, CH7, or whoever else purports to be showing NEXRAD) I'd see the same weather depiction at the same time.
2. If NEXRAD weather depiction is that different from ADSB, and iFly doesn't already, I'd like to see any available NEXRAD (acquired on the ground/internet), combined with (airborne derived) ADSB weather depiction, but some kind of visual indicator so we know which part of our looped WX RADAR depiction is NEXRAD, and which is ADSB. Maybe different colors, or similar colors with stripes, or something.
3. If possible, always show the weather a step up rather than a step down. So in the images above, the rain that is apparently there based on the weather reports and the WxUnderground image gets displayed even if it's depicted higher than it is. Personally I'd rather find myself flying in weather better than what was predicted/forecast/anticipated than worse. I'm not sure what to do if the ADSB stream shows no rain when NEXRAD indicates there is.