Which is the better HDD for Roamio upgrade?

I want to upgrade my Roamio from its standard 500MB drive to a 3TB drive and see most folks getting the WD AV-GP 3TB AV SATA II drive (WD30EURS), but I also see a WD AV-GP 3TB AV SATA III drive (WD30EURX) available on Amazon and the WD30EURX seems to have a better max data transfer rate, with all other specs being the same. Besides the superior specification is about a $10 lower cost.



So with that said, would the WD30EURX be a better drive for the Roamio or am I miss-reading something?



Thanks for your input!