It's meant to force Microsoft's hand and get them to fix the CPU overhead problems with DX on PC.

That may be the case, but there's no fixing Direct3D without gutting it. They've tried, they've gone as far as they can, and its still not good enough. If we see an API called Direct3D 12 it will be a very different beast methinks.

But that would be fine. Mantle isn't about control or vendor lock-in, its about evolving graphics programming and moving the state of the art forward. Whatever effort AMD will have invested in mantle will serve as prior art to the new status quo, and everyone will be happier for it. Supporting mantle won't be wasted effort now, because it'll just put you in a good position to support the new vendor-agnostic hotness later. Its not even that Microsoft (or the OpenGL ARB) will be more capable of developing a new 3D API, its simply because they are effectively Switzerland, acting as a mediator between politically-tense countries who can't be seen collaborating directly.

I'm very interested in Mantle, my main concern is not performance (still good to have), but doing some experimenting with new render tecniques, months ago I heard rumors about a new forward rendering tecnique from ATI, but found nothing about that, maybe now I'll see if that is possible. Does anyone know if it is possible to get symbols from Mantle even without the SDK? I'd like to try something already.

I'm very interested in Mantle, my main concern is not performance (still good to have), but doing some experimenting with new render tecniques, months ago I heard rumors about a new forward rendering tecnique from ATI, but found nothing about that, maybe now I'll see if that is possible.

I'm very interested in Mantle, my main concern is not performance (still good to have), but doing some experimenting with new render tecniques, months ago I heard rumors about a new forward rendering tecnique from ATI, but found nothing about that, maybe now I'll see if that is possible.

Pretty sure you can download the Forward+ sample from AMD's developer website as set if their Radeon SDK, or whatever it's called.

Link

In my opinion there is room for both more lower level APIs like Mantle which one would only use for performance reasons and room for more higher level APIs which one uses if one wants to have shorter production times. It all depends on the application if it makes sense to choose Mantle.