Dual Flush and HE1.28 gpf mixture

I have a bit of a dilemma on my hands with the WE calculations. By owner request, we specified dual flush toilets throughout the building. After a preliminary look at the calculations last year, I realized that we may be able to maximize water savings by specifying dual flush everywhere EXCEPT in male bathrooms with urinals, where we should spec 1.28 gpf toilets. This idea is a bit convoluted, but is based on the calculation philosophy used in the 'Water Use Reduction Additional Guidelines' document. EXAMPLE (all based on equation 4 from the guidlines: http://www.usgbc.org/ShowFile.aspx?DocumentID=6493): male & female combined, dual flush, urinals, FTE occupants weighted flowrate=1.35 female (separate from male), dual flush, FTE occupants weighted flowrate=1.2666 male (separate from female), dual flush all locations, urinals, FTE occupants toilet flowrate=1.6, urinal flowrate=.125 male (separate from female), dual flush, 1.28 mix, urinals, FTE occupants toilet flowrate=????(but should be less than 1.6), urinal flowrate=.125 Now I have a mixture of bathrooms and fixtures (individual with 1.6/1.1 toilets, male group with 1.28 toilets and .125 urinals, and female group with 1.6/1.1 toilets) and no way to differentiate them in the calculations. Its simple enough to separate out the female component, but there is no distinct way to separate the male users based on location in the building. Has anyone else run into this problem? I could just average all the male at 1.28gpf since it realistically shouldn't be any higher than that, but then I'm not utilizing the savings from all the pint urinals. I've also thought about using equation 4 as above, but treating the urinals as part of the calc and applying some type of ratio of individual:group bathroom usage. Thoughts?