I have tested a technique to completely eliminate noise* on digital images based on the signal/noise ratio improvement achieved through overexposition.
At the same time this technique extremely expands the dynamic range of your image in the shadows (don't think of HDR, it's not like that) and recovers in high detail all textures present in the darkest areas of your image.
* It actually does not eliminate noise at all, just takes for every pixel that one with the best signal to noise ratio. That is why textures are not only 100% preserved, but improved.
To do this you simply need to shoot twice making use of a tripod. One shot will be as usual, keeping highlights unburnt. The second shot with be done with a severe overexposition (I found +4EV to be a good value). A simple piece of software merges those two shoots into one final image with no noise on it and fine detail even in the darkest zones. I have converted my modest 350D in a virtually noise-free digital camera with 12 f-stops of real usable dynamic range.
You are really reinventing the wheel here. Blending together the best parts of frames shot with different exposure levels has been around several years prior to HDR blending being added to Photoshop as a feature. I've been doing so since 2001 or so when I got my first digital camera.
Your technique can be easily duplicated in Photoshop without any special software plugins. Shoot a frame with normal ETTR technique (don't blow the highlights), and a second frame with +3 stops exposure. Process both RAWs with identical settings except for exposure, the second one processed with exposure set to 3 stops below the first. Stack the second exposure on top of the first in Photoshop, with layer blending set as follows:
Split the two halves of the "This Layer" white slider apart by holding down the ALT key, position them as shown, and you're good to go. This will make luminance values of 220 or above come from the normal exposure, and luminance values of 35 or less to come from the +3 exposure layer. All intermediate luminance values are blended from both layers so there is a smooth transition. Setting the white blend point to 220 keeps saturated colors with clipped channels from contaminating the highlights, and seting the black blend point to 35 keeps the worst of the shadow noise from having any effect at all on the final image. Having a 185-point luminance blend range makes sure that there are no visible seams in the blended image. You can save the layer blend settings as a preset for convenient later use.
I've used this technique successfully for many years.