Andy,I have rolls of this stuff it is amazing!
However, I'm still not convinced about the dielectric strength (the Welsh sparky) of heat shring, say thickness 0.5 mm even at the strength of that tape it would not take much to reduse the insulation proerties at a nick.
Say 33MV/m that equates to 33kV/mm, take a 3/4mm nick that reduces it to 8.25kV.
OK well above what we would see, however if that happended at install then this could easily be reduced over time due to many environmental & mechanical factors.
Most of the failures I've seen have been on industrial machinery and almost certainly due to mechanical vibration damage.
It does not however stop the failure occurring.
Paul