alt Hacker NewsCorrect (although the nightmare part is a bit exaggerated since return-oriented programming showed that non-executable stack does not help a lot). GCC can also put the trampoline on the heap, but this also has downsides.
For me the main downside of trampolines is that the optimizer can not de-virtualize the trampoline again. This could be implemented, but avoiding the creation of the trampoline in the first place is much better.
That's what it felt to me like. With non split stacks you're mixing return addresses with potentially entrusted data. You're already living in sin. With split stacks a trampoline wouldn't be a problem.