Not sure about the torch changes, I can see myself dungeoning and not being able to find my way out again.

Biomes should be interesting though.
What method of mining is everyone using? I think (from screenshot) that Dowly just dug a huge hole (strip mine? or was that a giant bowl for frosties?), how did that pan out for Ore? Or, were you more interested in cobblestone?
I have developed a branch mine starting at bedrock level (adminantium). Currently it's only 3 levels high ( but each level has a central corridor, with 20 branches each side (40 total), spaced at 3 blocks apart, each at 20 blocks deep. Took some time but the payoff was worth it.
8 x 64 Coal
2 x 64 Diamond
4 x 64 Redstone
3 x 64 Gold
1 x 64 Iron Ore
Not too mention a shed load of Cobblestone, which I'm now using to construct my citadel.
Unfortunately, I can't render my mine as Cartograph doesn't seem to like my added mine system and all the torches.