There are mainly three types of tube chain conveyor now .
1.Tubular drag ring chain 2.Tubular drag cable 3.Tubular drag plate chain

Tubular drag cable is mainly used for food industry ,becasue it has better performace in protecting the fragile material.
Ring chain and plate chain mainly used in chemical industry.

The advantage for tubular drag conveyor is ---3D installtion ,less power and noise.
The disadvantage is the wear of the disc,I agree with your idea.

If you want to replace your bucket elevator,please considering the material's details.
Tubular drag chain conveyor can not lift material vertically if it has a very good fluidity(something like cement or liquid)