I guess it will depend on how AsRock have connected that LSI SAS controller.
Z87 has 16 PCIe3 lanes, and 8 PCIe2 lanes which connect to the PCH.
If you have a single graphics card installed in one of the PCIe3 x16 sockets, even if they use a PLX Technology Gen 3 switch such as the PEX8780, you're going to be sharing bandwidth and adding latency.
Go to a crossfire or SLI graphics card setup then you lose even more bandwidth.
I would have to assume that the LSI controller on that board would connect to x16 PCIe3, as the PCH doesn't have enough bandwidth.
I would wait for SATA Express, which should appear in some form on Z97 motherboards, most likely from a 3rd party, but we'll have to wait and see.