I think it is a good idea and a bad idea. it would be nice to see the like of some of the worlds top drivers race, but it would also stop people that have race hard to get there, from getting an entry.
Maybe an 'exhibition' heat or something like that would be better, and make it for a certain round of the series so that people know when it is going to be.
But it would be nice to see them race.
Maybe a yearly one off invitaional organised by the brca.?