I think one of the major reasons LeadCheck was not recommended for use on drywall originally is because it can create false positives. Doubt it has changed unless they've changed the tests. It may be worth keeping in mind. If you test drywall/plaster and "find lead", it may be a good idea to retest it with D-lead just to be certain.
I read the procedure. Why on Earth would anyone with more than a very small project want to fool with swabs when accurate XRF testing which causes no damage is readily available? The cost is the same as or lower than the cost of the swabs for all but small projects, especially if the consultant is able to fit the smalelr inspections in with other work on their schedules .
In states such as California a Lead Inspector has to perform all lead inspections, and a good Inspectors would use an XRF.