> (we actually we gain one X1). And we gain [...] sound output.

Here I think you counted one and the same thing twice. *Either* the SB800 gains us audio (but no additional PCIe) *or* it gains us one x1 (but no audio over the other solution with dedicated audio chip or card on x1).

> You must admit that two SATA controllers is somewhat limited.

For me personally, two SATA controllers would be sufficient.

> the simpler option might be the more sensible one.

I second that.