I would expect the breakdown of residue in a long term no-till field would be much better even on BT corn with the amount of soil life present.  That history has to be factored in (although probably not easily) as one considers side-by-side comparisons of various tillage treatments AND has to occur over the long term.  That is a hard concept to get through to a farmer who's seen a heck of a conventional corn crop on an old sod or hay field.  A one year comparison just isn't a fair assessment.