After a lot of trials with several recent Cameras and a good raw converter, I have decided to change my "high ISO image processing".
Why
Simply because the fine noise is really more acceptable than the smoothing, especialy for grass, branches, and foliage.
With LR5 and a G15 (ISO 400 to 6400) for example, I use only 10 for luminance (detail 10, contrast 16) and 16 for color (detail 10, smoothing 16).
OK, noise is visible from ISO800, but no artifacts or exagerate smoothing.
And it appears to be more acceptable for prints AND screen !
The most important thing is to remove the color noise, the luminance noise is more acceptable except for the sky.