AMD doesn't exactly do an amazing job of avoiding gotchas in their CPUs. They have a bizarre idea of what writing zero to a segment register should do (resulting in info leaks that were only recently fixed on Linux), their demented leaky IRET is even more demented than Intel's, and their SYSRET's handling of SS is downright nutty.

OTOH, Intel's SYSRET is actively dangerous and has resulted in severe security holes, and Intel doesn't appear to acknowledge that their design is a mistake or that it should be fixed.