Since we have Chisels & Bits already, I'd like to avoid redundancy on an already heavy pack.

In particular, I'm thinking of the stair, slab and wall variants of AbyssalCraft blocks. However, any options useful for us at BTM are more than welcome.

With the ID shifts caused by removing a block from an existing world, not to mention potential structures where the block might be incorporated, it might be easier if I just make a custom BTM version where redundant blocks are gone by default.

With the ID shifts caused by removing a block from an existing world

This is meant to be a configuration option. Besides, last I checked 1.12 doesn't have ID shifting issues?

I get the structure concern, though. In this case just don't do it. We'll be fine.

I've stayed clear of config options for disabling blocks since that's generally been frowned upon. But if ID shifts no longer happen, then there won't be any problems.