From my perpective the main reason to do the QC check is to make sure that the project will simulate. Errors must be fixed to run a simulation however fixing the warnings is optional. The warnings seem to be deviations from the default values. I always like to look through the warnings because one of the items that I always get a lot of are missing schedules some are important some are not. Other warnings that I see a lot of are wrong wall types, which I always fix, and missing fans or incorrectly sized equipment. As far as incorrectly sized equipment is concerned, I would never want to rely on Mkt Mgr to size everything. Mkt Mgr is at it's best when it is comparing scenarios.