I have had some brilliant luck!
Today, I tried the S-OFF hack on my HTC One.
I went up the moonshine route, but you can also try revone.
after doing this, I rebooted, reapplied the install zip files and rebooted again.
installed the rSAP app from Play, and BINGO everything now works!
Looks like there is some additional write protection that wasn't allowing the files to write properly.
All good now though - works like a charm!