O horizon and soil function

I am working on a draft HGM model (hydrogeomorphic method of wetland assessment). I want to establish descrete values for
the depth of the O horizon related to the functions of infiltration and water storage. The particular wetlands we are assessing are
mineral flat wetalnds. These are as named mineral soils with 0-2% slope and diciduous vegetation on the Mid-Atlantic Coastal
Plain.

HGM models use a scale of 0, 0.1, 0.2.......0.9, 1.0 to scale characteristics that can be recognized in a field evaluation. I am
finding that ~4cm of organic matter is typical in an otherwise highly functioning wetland and am considering that is a 1.0 level
which represents a high function for infiltration and water storage. Some soil scientists, for whose opinons I have great respect,
have said the high function of 0.1 should be at the diagnostic margin for a Histosol (20cm). I don't agree, and would like some
other opinions. Please advise