Im feeling way too lazzy to read all the posts, but heres my personal experiences.
Aircooled eclosures: Nexus drive-a-way is a no no, temps go way too high and doesnt really do much for noise. mCubec Vertical Silence, so far the best commercial enclosure i have tried, having good contact with the drive to reduce temps and actually reducing the noise quite a bit, but not suitable for passive(no airflow at all) cooling.
Homebrew enclosure alá Alleycat, best of the aircooled options, lowest temps and lowest noise. Search forums for details, the thread has recent replies. works well even witout much airflow. enclosures from www.elfa.se
I havent tried the SmartDrive, mainly because it isn´t available here.
Watercooling, Aqua-Computer makes aluminium blocks for one or two drives wich cool well but are not that good at reducing noise. Putting two 250Gb samsungs in one of them, and enclosing it in thick foam from Biltema makes them inaubidle from any practical distance. Impossible to hear more than 4" away, without the foam audible from the next room. Temps stayd at about 38°c in 22c ambient temp, cooled by a reserator in the same loop with a 24/7 folding 3700+, X800GTO and nF4 chipset. The quality of the blocks is also pretty damn impressive, though you can´t admire that when they are enclosed in foam.
The block+foam takes of quite a bit of space, but it´s as quiet as you´ll ever get in any practical way and not damaging the longevity of the drive with insane temps. Wthout the foam they dont do anything for noise without mods, but they will cool a drive with zero airflow.
Theres also a copper cooler for two drives called SilentDrive(iirc) that should do at least as good of a job as the Aqua, but i haven´t tried that one.
conclusion: aircooled, you need airflow to keep the drives cool in the commercial boxes, though SmartDrive owners may have a differnet opinion. watercooled, combined with foam it´s the best option after the homebrew enclosure, and apart from a couple 90° bends doesnt increase resistance. The stock res pump runs all of the above no probs
And as far as the Raptor noise goes, my 74 is brilliant
Quieter and smoother than any of the five or so nidec Spinpoints i´ve had
I blame the Whisky for any typos or other mistakes
Scotch & Canadian= Whisky, Irish & Yank = Whiske