This paper reports on the IR system level modeling for a FPA based on type II superlattice photodiodes. The predicted performance of the super lattice detectors is based on published values from device models and measured results. A top level description of the sensor model is given and how it is used to determine system level trades. Results of these trades provide valuable feedback to developers of type II superlattice devices, arrays and readout circuits. Trades between IR FPA technologies can be made to aid the IR system developer to make informed decisions relative to risk and performance early in the program cycle. IR band selection is a complex trade of target signature, background, detector technologies and optical response. This paper explores these considerations for single and multicolor applications.