In my opinion (it's free so it's worthless) the racing photo looks better without noise reduction. The noise/grain gives it a more realistic quality. For the people photo, it's a toss-up. I would probably go with the reduced noise photo but they seem close enough for the noise to not really matter for me. The IA definitely helps the last photo and, if this type of scene was something I often encountered, I would be tempted to use this software.
Thanks for posting this.