As KTT will fly the Airbus soon (I assume), he'll find that t/o performance on the bus is based on contaminant and depth, and apart from crosswind recommendations and disallowing poor BA on icy runways the BA does not affect the performance calcs. If manufacturers cannot standardise perf calcs for contaminated runways all power to a capt who shows this iniative. BTW for those who ask what an investigation will say if you go off a contaminated runway having inspected the runway yourself. Remember the Boeing contaminated performance tables are "ADVISORY ONLY". Just blindly following advisory tables and having an incident will more likely get you into hot water.