My conclusions on DX10 water are that (leaving aside the extra bump maps and white caps) the shader logic is fundamentally the same as DX9.
Light coloured water looks much paler in default DX10 only because the specular defaults in the shader are different and to a lesser extent the fresnel max/min values are different . Here are some further screen shots showing conditions which exhibit a significant difference between DX9 and DX10
My Tweaked DX10
And for interest here is the DX10 shader from FSXCLite by Striking Software which shows a very different tuning. This uses a more sophisticated algorithm for reflections, but suffers to my eye from a shimmer along the far shore.
Now another scene at Bowerman
The third scene has darker water and the variations seem much less.