Very pleasing photo, Jim. I like the stones in the foreground. These with the curved river back leads the eye to the mountain. This is a good example of foreground, middle ground, and background in a photo.
The two stop GND filter is the correct choice. That is generally the correct amount for balancing a scene and its reflection in water. As a result the mountain and the trees are in proper tonal balance with their reflections. Without the GND the reflection would be two stops (4x) darker.
The 5 stops of ND was also a good choice as it enabled the slow shutter speed which gave you the long motion streaks in the water. Without it the shutter speed would have been a factor of 2**5, 32x faster, (or about 1/6 second). Those streaks would then be very short staccato stabs, and not pleasing to the eye. The long streaks help to break up the dark central portion of the photo, which might have otherwise overwhelmed the picture. Without the streaks we would have a more exact reflection of the trees. Exact copy reflections are often pleasing, especially in still ponds. A still reflection would have been misleading, and we do not want it here. The long streaks emphasize that this a fast moving river.
I might have liked a little more red in the alpen glow, which was probably present in reality. But if you exposed for that, everything else would have been darker also. The trees would have become a black hole in the center of the photo which is never desirable. I like that we can see some truck and branch detail in the trees,
A contrasty scene like this provides many challenges, and I believe you met those challenges very well.
