I learned the hard way that RAID is NOT supported on the 6GB/s ports on (any version of?) the P8Z68.
They way ASUS writes on the site could be a little misleading
"Intel® Z68 chipset :
2 x SATA 6Gb/s port(s), gray
4 x SATA 3Gb/s port(s), blue
Support Raid 0, 1, 5, 10
Support Intel® Smart Response Technology "
^ This means that RAID support is ONLY for the 4 x SATA 3GB/s ports
As far as the marvel controller goes, i'm not sure - but from what i've read around, it seems unlikely.