Well here are some technical calculations. Take from them what you want.
The Iray RH 25 at 100 yards calculates to 1 FPA Pixel per 2.96 Sq. Inches of viewing area. On the viewing screen it calculates to 2.4 Screen Pixels for every 1 FPA pixel.
The Voodoo S at 100 yards calculates to 1 FPA Pixel per 2.13 Sq. Inches of viewing area. On the viewing screen it calculates to 1 Screen Pixel for every 1 FPA pixel.
So the Voodoo has a slight edge on the FPA pixel (Powah) and the Iray RH 25 has a slight edge on the viewing screen (Powah).
Then it boils down to the magic in the software rendering algorithms which I do not have a clue about for either unit.
Is there any info to suggest that the rh25 is running a different sensor or screen than the mh25, or is this just an mh25 in a weapons rated case with an already installed eyepiece?
My understanding is that the mh and rh guts are the same, since the specs are otherwise identical.
If that holds true, then as someone who has owned both an mh25 and a voodoo, I will say the image quality is better on the voodoo. Is it 10k better? That's the better question...
But that's using it as a monocular. Once you start using it as a clip on, the voodoo will quickly out perform the iray. The narrower fov of the voodoo will help it be usable at significantly higher mag ranges than the iray. From the partially rounded image through the iray, I suspect there is already some eyepiece magnification happening that causes clipping off of the corners of the image, which leads me to think it may degrade even more quickly under additional optical mag, but we'll have to see about that.
I think that the use case for both of these units are a bit different. I think the iray is an improvement on the mh25 in regards to usability on a helmet mount. The visible image appears to fill the eyepiece better on the rh25 than it's mh25 counterpart, so I think this will likely be a more pleasing image, especially if trying to run it dual band with a pvs14. Unfortunately, this comes at the expense of extra weight.
Because of the wider fov of the iray as compared to the voodoo, I think it will work better as a helmet mount, but the exact opposite is true when using it as a clip on.
I think the iray will likely work great for someone who primarily plans to helmet mount it, but would like to be able to use it as a close range clip on as well. I think the voodoo will work better as a close to mid range clip on, with the ability to mount it on the helmet