wburton72 wrote: [ ... ] and possibly terrain smoothing which would make the world look a little more organic.
You say 'possibly' and 'a little more' so perhaps you mean something subtle?
I feel a small degree of 'smoothing' can be suitable for the Minetest, i have been working on this in my slabrealm mod
http://forum.minetest.net/viewtopic.php?pid=85502#p85502 which creates a new realm in the atmosphere with a layer of half-voxel slabs for the less extreme terrain. Underground, caves and high rocky mountains are left full-voxel. The slabs enable walking without jumping over the less extreme terrain. The generation method is very simple and only requires a very slight increase in calculation, not a doubling as you might suspect.
I can assure you that during testing i spent hours exploring slab terrain and after a while you start to appreciate the voxels more because you have had a break from them, some variety makes you appreciate both types of terrain more, i certainly would not want to see everything smoothed to slabs.
Watching MC videos i've noticed how some add slabs to a landscape because they get fed up with constant jumping. Slabs could have a place on smooth plains and deserts to ease walking. Also, smooth flattish cube-voxel terrain tends to lose some definition which slabs bring back by adding extra contour lines.