Kernmaster plain and simple Best multiple use line. Isn't as static as some so if your looking strictly ascent I'd recommend your first two options. PMI being less stretch and more rugged, HTP being slightly more flexible and brighter colors.
If your going to be using it with work positioning...
Re: RW advancement with hand ascender?
Here was my set up with the stitched stiff tether. I added a shackle that i attached my ascender too.
Stiff tether with shackle
Hope this helps answer your question.
Re: RW advancement with hand ascender?
I attach an ascender into the top of my RW tether and that pulls my whole system up. Here is an old video. Its changed some as i now use a stiff tether. But you can see the same concept.
RW frog walker
Vortex is my big tree rope for SRT. I think it works great with the zk-2 never had any problems getting it in. I also use 10mm armur-prus. The stretch is minimal, def easy to grab. Its a little thick for handled ascenders. I haven't noticed any problem with foot ascenders. Recommend it.