The main issue with world height changing mods is that mod-added ores don't scale their maximum heights to the world height - that means you will only find IC2 copper under level 70 no matter the height of the world, for example. With some small fixes to ore generation, IC2 ores can be world height independent:
This scales the randomizers to be based on the world's sea level, letting you find tin on up to level 80, copper on 140, and uranium on 128, on a 256 high world with sea level 128. That's a lot of digging for tin though, but the taller the world is the higher is the benefit.