@Trev
In terms of functionality, UAE would be just as capable.
But in terms of performance, not.
There's no reason a proper design couldn't take advantage of multiple execution units to implement the asynchronous parts of the system
Except that there really isn't any asynchronous parts, everything must be really tightly syncronized to get proper emulation.
or even offload emulation tasks like recompilation.
If JIT would be implemented it really wouldn't be worth the trouble to use SPEs for the translation. SPEs have akward (read: no) access to the main system memory, and the actual translation takes relatively little CPU resources -> just use the PPE.