Probably depends on what types of "DCI things" they incorporated in their shows. When the Southern Knights, from the UK, came to DCA in 1990 I believe they were using multi key brass. This was a decade before multi key was approved in DCI. The massive electronic DCI pits would certainly be an issue and would, as a minimum, result in penalties. From the start DCI has made allowances for age and some instrumentation in non North American Corps.