PU hoses need to fit very tightly over the inner rope, I even prefer to force it over the spliced on the end to prevent sand and dirt creeping inside the tube. This way the PU wears down with the rope inside untouched.
All the problems with PU comes from lazy design and manufacturing where they fit a small rope in a too large tube without sealing the ends. With sand then entering the empty space between the rope and tube you get wear on places you can't inspect wich are indeed a safety hazard.
My SK99 300 line weighs 1.1g/m and SK99 500 is 2gr/m
Here is how I do both ends of the depower rope on my carbon bars:
Evan - Infexion