I hope you dont mind a little objective opinion.
remove that plastic fan holder on the back and replace with ear grommets. They are way better.
I will when I remove the grill, but I don't know how much it'll help, it doesn't get much quieter when I put my finger on the hub, though I guess it could still be vibrating when stopped, and it could vibrate more when the ball bearings wear out.
regardless what speed, less fans is less noise. I find that 1 fan at 7 volts is quieter then say 2 at 5. if you can try and use the intake fan to hit both hard drives so you can dump the other fan I think there will be a noticable difference.
They're not both on actually, since both hard drives aren't usually on. When they are, the fan ramps up quite a bit, though the coil noise from the FSP seems to go down significantly. Rather ironic, a JVC spinpoint reducing whine, I'm hoping that when I try it with just the spinpoint, the coil noise will be gone or greatly reduced.
I don't think using one intake fan for the two drives would work at all. I'd have to move the spinpoint onto the styrofoam platform, then the drives would be over the edges a bit, and the spinpoint does have a whinny JVC motor and having it at the back with all that stuff in the way seems to block the whine somewhat.
At least it should be I cant tell what the other fans are or what speed they are at.
Cheap zalman fans at ~3-4V(33 ohm resistors).