Thing that struck me as strange with both of these manufacturers tho is that on their mobos they quote SATA2 - the controllers in the typical southbridge area had the sinks physically taken off to reveal the newer marvell chipset.
I have a weird feeling that these could be some kind of SATA3 tech stapled onto SATA2 buses or similar, that will give a SATA2.5 result as a sort of interim.
All spectulation ofc - what I would say is tho - pay particular attention to ALL the SATA ports on the mobo when u review them. I'm envisaging something along the lines of... 6xSATA2 ports plus 2xSATA2"enhanced" ports, iykwim.
OC3D got an ASUS P55 review on the sidelines ?