If it were up to me, I would do as Mitch suggests, spec tire. Then I could go to the tire mfg and get some money for specing their tire. Is the Yellow a better tire than YHC, duh, its not apples to apples. It is much softer. Is it better than a YHB, same duro but the YHB will kick its ass in intial grip.
What screwd this up was last year we allowed the Yellow as we thought it was a hard tire. When MG changed it to a softer compound, we let it stay because so many had already bought tires. But this year we can correct a mistake. That is why the yellow is out.