I've got pretty much every noise reduction product in my collection (see links to screenshots and examples
here under "Noise reduction"). I just tried (from the bottom of my sample image up, after the original) GEM, Noiseware and NoiseNinja at default settings on a noisy 4MP time exposure of a southern California forest fire from a few years back. (This small fire grew much larger and made the news!). Noiseware seems to do the best job--even removing some dead pixels the others left behind.
Of course you'll want to try demos of GEM and any others for your own tests on larger examples made with your own camera. The current 2.1 version of GEM didn't like my 2.0 serial number anymore (it may be linked to an earlier OS than I am using now), and doesn't work on images under 512x512, besides performing the poorest of the three–so I don't think you're missing anything.
FWIW, based on the stats of visitors to my site, they are most interested in
Noiseware (the top search phrase so far this month and the 5th most popular page visited). It's the noise-reduction plug-in I personally reach for first.
Also, the guys who originally developed the Kodak plug-ins moved on from Applied Science Fiction and are now running
Image Trends. I've been in touch with them since 2003 when I first tried GEM.
