Stack HGB is a very commonly used bridging method, more so than flat hgb. There are many in the 0cps community with strong pbs and I think that the wr would receive even more competition if it was made into a main category. It is a variation of flat hgb, but Cha Cha gain is also a variation bridge and is in the main distance category and I think that stack HGB deserves to be in it as well!