For me, it's about more than just noise. I tried Noise Ninja, and found it similar to DxO (and better than DPP and PS) for what it does. I haven't tried Topaz. However, DxO is a complete package and it's lens corrections are better than those available with ACR.


Here's an example of multiple corrections needed, noise, sharpness, and especially geometry:


[img]/cfs-file.ashx/__key/CommunityServer-Components-UserFiles/00-00-00-35-15/Art-Appreciation-Uncorrected.JPG[/img]