Raid 0 doesn't improve performance that much, in synthetics is does, not so much real life scenarios.
Also you'd probably be interested in the Thermalright IFX-14, it's about 10$ more and shaves another few degrees off.
I hate case clutter thats why the floppy went out for me, if I ever need one I have a few laying around that I'll just stick in.
Where are you seeing this information regarding the hard drives? I'm interested and surpirsed to hear this, as the disk gets fuller I believe the 1TB drives dip a little bit more in performance then other drives, but thats about all the negative I saw when compared to other platter hard drives.