Using different energy rates between CHP Proposed and Baseline

I know that the 90.1 and the LEED Reference Guide generally tell you to use the same utility rate structures for both the Proposed and Baseline models. But what happens when the Proposed model uses Full Accounting of DES and includes DES-CHP-supplied electricity and steam, while the Baseline uses On-site Boilers and grid-tied electricity? The DES is charged $0.45/therm while a new gas service at the Baseline Project Building would be charged $0.73/therm due to inherently different rate structures). I've provided a link below to a CHP LEED Calculator (provided by the EPA CHP Partnership) which instructs the user to use $0.45/therm in the Proposed model since it is a special price for CHP gas and $0.73/therm in my Baseline model (See Inputs tab, rows 14 and 17). Is this acceptable from a USGBC perspective? Thanks! http://epa.gov/chp/documents/chp_leed_calculator.xlsm