Benefits include things like less memory fragmentation, faster and more efficient memory allocation and de-allocation, much more robust virtual memory implementation and finally automatic stack enlargement.
Between 30 to 50% of all crashes on the Amiga are due to programs running out of stack-space.
With OS 4, this won't happen anymore as the stack can be automatically enlarged when the system detects a program is about to run out.
Well, programs running out of stack is a problem caused by sloppy programmers, it shouldnt have
to happen at all. Better spend time on learning people
to handle recursive algorithms properly.
It is strange people seems to have such a problem with using StackSwap()

I hope it doesnt add too much overhead.