Spotting enemy in a limited terrain hex from an elevated spotting hex

[plloyd1010]

In real world terms, you can see the copse of trees from even further away, but you certainly can't see into them any better just because you're up high.

Now how about making things muddy.
If trees are involved, woods for example, being higher would be a disadvantage because the the canopy gets in the way.
If it's about buildings. Looking obliquely down into the town or village, it looks about the same as looking from the same elevation.
If looking into a field, being higher would likely be use full as one can look into the field better from above.

So in case you want different types of limiting terrain, that's where I would start. I can think of making things complicated.