RSX was also not unified. A lot less efficient potentially.
If you think about it, unified and more effcient vs. not unified and more peak performance could be exactly what we're looking at once again, just in a broader sense
If Microsoft really went for a fully integrated HSA design, wouldn't having some very low-latency SRAM (basically a really fast, shared, chip-level cache) + a lot of DRAM make way more sense for them than going for lots of bandwidth?
If SONY really had a bunch of HSA enbabled, yet more specialized hardware components "glued together" on a multi-chip level, wouldn't going for lots of
bandwidth in between them make way more sense than having a huge
amount of memory?
Basically, if two or more heterogeneous minds could actually
think together without having to
speak, they could (and should) prioritize low latency over bandwidth - as the data directly shared between them in the process of achieving common results typically came in rather small, but very frequent chunks.
If two or more heterogeneous minds could efficiently co-work on a wider set of tasks, but had to communicate their more individually compiled results in order to achieve their common goal, they wouldn't need to meet
that frequently, but there would be a hell of a lot information to communicate between them ...
The latter approach, though having some obvious disadvantages and being less efficient, has two main pros: It takes less mindwork to realize and - specifically
because it is
not completly unified (andrather relies on multiple chips glued together) - makes it a lot easier to bring more specialized team members in ...
If I was a Trekkie, I'd probably break it down arguing that Microsoft seems to strive for a perfectly synchronized BORG Collective while SONY likes to keep their stuff way closer to the United Federation of Planets ...