> its possible to downgrade flash on some models.

Only on models the required firmware version was originally released for, which means pre-slim models.

> GFX and CPU are great. [...] you get BlueRay, nice GFX, great great CPU

If you say so...

> with many SPUs ...

MorphOS would have to implement support for them first. I doubt this would be worthwile given that such code wouldn't be usable on any other current or future MorphOS platform.

> Maybe someone could somewhat add some RAM to the board?

Such hacking would be no basis for undertaking a MorphOS port.

> does MOS have virtual memory?

In case you mean memory paging/swapping, the answer is no.