> with those configuration I still don't understand why X8 and X1 aren't an option

I don't understand either the reason there's no full configurability but 29 different fixed configurations you have to select one from. But Freescale told you so, and we have to accept that as fact for now.

> the X4, X4, X1 configuration is not a big loss (having one X1 in place of the last x4).

It's one x1 more, so all four PCIe controllers used in this configuration (and moreover, it's the *only* configuration with all four controllers used).

> Are you telling me both SATA ports are run with one PCIe lane?

No, I meant to tell that both configurations '0x10' and '0x2' have two (i.e. all existing) SATA controllers connected (using 1 SerDes lane per 1 SATA controller). Just look at the configuration file you thanked me so much for linking it. It's all in there.