Your mod is brillant, although I find out that some elements might be better:

1. More defiled blocks variations such as cobblestone, iron bars, diotire, andesite and granite with correct replacement in generated structures.
2. Replacement for stairs and slabs
3. modded ores "defiled" variants
4. Optionally dynamic trees support (just take dead oak tree model from BoP compability with authors permission of course)

I replaced some blocks in roguelike tower with modded purplish blocks to represent you what's in my mind:

For 3 and 4, see #4 and #21.

For the rest, I'll see what possible, but it's likely with my current future plans most of them won't be added once I get back to working on this mod. Still I'll try to keep in mind the blocks.