Hilleberg do not joint their poles but they have had problems with their 9mm alloy poles on Nallo 2 and 2GT models. Oddly, or maybe not, the poles on a 3 and 3GT don't seem to suffer the same way. Hilleberg are at least good enough to replace faulty poles though.
I notice that the poles on my new Nammatj 3GT are 10mm and not tapered, rather sleeved at the joins.