You stop down a camera lens to improve visual acuity i.e. sharpen the image.
If your eye pupil does't expand to 7mm, the scope is effectively "stopped down" to your pupil size. Depending on the individual samples compared, the 6x36 may render a sharper picture
There is so little difference between the two it comes down to personal preference. Do also prefer the 6x36's creature features.
Increasing power would make a bigger difference in low light performance.
Probably the only advantage to growing older is smaller objectives perform better than they used to in low light and thin reticles no longer fade before it is too dark to shoot...:)
