Have had mine now for a few weeks, and so far no coil whine at all and to be honest, unless i get up and put my ear right next to it, i don't even hear the fan running, and when i do listen up close it's just a light fan sound. And that is after 3 hrs of Demons Souls.
I've platinumed Astro, played a ton of Demons Souls, and now alot of Sackboy also, and i've been blessed i guess by having one of the "silent" ones.
I feel really bad for you guys that are having the bad coil whine. For what it's worth here is my setup for where it is....plenty of space on all sides, vertical, and i use ethernet, not WIFI.
I hope you guys having the issues get it all sorted out. I read how some of you are getting that buzzing noise right out of the box when you first start up your replacements from Sony. That definitely is bad hardware, or faulty QC, or a combination of the two.