The braided wire can wear through the plastic tubing.
My comments were related to plastic inner sections, not braided wire.
Increasing the sleave ID or decreasing the cable OD would help the friction problem, but would introduce a lot of slop.
Not sure that you have exhausted the options available since this has worked very well for me and a bunch of other folks. The 'slop' you mention would not be problem with a small difference in outer diameter of the inner tube.
If you still want to try/use a lubricant, I suggest the "
3-in-1 Professional Lubricant wirh Teflon".