The WAT limit for the associated RTOWs considers the FAR25 en-route climb requirements at the MSA
How exactly are you doing that?
I've mentioned before that I don't do the P/E for the aircraft that I actually fly, and there's some horrendous CFIT possibilities built into the procedures employed (which stop short of MSA).
Having met your colleagues in Seattle, I understand that they are using Boeings SCAP compliant takeoff chart program, this unfortunately is pretty limited in the sense that it cannot calculate data based on you returning to a holding point, climb to MSA and then provide a weight for FAR25 enroute climb requirements.
For a lot of larger companies, if the solution doesnt come from the manufacturer, it wont be done.
Around here, we attempt to bring all OEI's to a final holding point, the crew can then decide on their next course of action.
Mutt