Once klee slab behavior is implemented it'd be nice if the slab you tried to break has the same harvesting behavior that a lone slab would. i.e. same hardness, explosion resistance and harvest level

This is now partially implemented. Whilst I don't have the klee slab behaviour yet, the block hardness, harvest level etc. does depend on the slabs which make up a double slab

nice. keep up the good work

This will finally be added in the latest version! The blocks now break separately in survival and the speed of mining the individual slab depends on which tool you are using and for which slab you are targeting!