Because our track rules are pretty loose, I run exhaust retainers and lash caps on both sides of anything I put together. It's more valve train weight and probably a touch of a disadvantage if you're stuck with 10.8's, but the added reliability is worth it.
I have to agree that many of the rules seem to be created around the revolving door of a throwaway engines and the associated repeat sales, instead of reliability.
ASN and Seattle's karting club all run these on their GX200's with 18# springs, have been for years.