I have avoided PCA events because I know they have safety concerns about our cars. You have to have a instructor sign off on your driving and you have to provide him/her w/race seat, 5 point harness, arm restraint, all properly installed, per their opinion, not yours. None of my cars ever fit their rules (incl present 2, 1 of wh/has no passenger seat). When I have done PCA events in my other cars, they were well run, but way too many drivers, cars, and run groups for my tastes, so never felt I was missing much by being excluded in my Caterham.
All that being said, I do respect PCA and their desire to make events safe. Ditto Audi club and BMW, all of whose events I have done and are clones of PCA.