I have used heat-shrink on my extractor hose, and it worked well. It seals well and looks like it was always part of the hose.
I have a DeWalt extractor (truly terrible vacuum, BTW, will be replaced with a CTL26 a.s.a.p.) and tried to run a cable inside the hose to copy the Festool plug-it suction hose. I used heat shrink to seal the points where the cable entered and exited the hose. (It didn't work at all well and took every opportunity to block; I think the Festool hose is larger diameter for the length where the cable runs inside.)
I did consider other options, such as Duck tape, but figured I might just get a sticky mess either side of the wrap as the hose flexed over time.
The only downside of the heat-shrink (any extra material, in fact) is that the hose is slightly stiffer over that length.
Andrew