Less Noise=Less detail?
Yes. Anti-noise blurs image detail. Some are better than others. The better ones tend to be available in external post processing software because you can fine tune them to your taste and output (screen or print size). IMHO the cause is too many megapixels crammed into a small digital sensor because most consumers value quantity over quality.
In my opinion iso 400 and above are best left to a camera with larger sensor than a G9. A larger 6mp DSLR will outperform a G9 with respect to noise. The tradeoff's however are weight, learning curve, and expense. This is true regardless of which brand of dslr or compact you buy.