This question came up at the performance troupe I run, I have two of the early builds that I have been making for people over the last six years, these were the original design that I subsequently refined and been supplying to members there after.
Nothing special, standard tube poi, which are now generally used for teaching purposes, and thus have a fairly heavy usage pattern, looking at them critically last night they are a little thinnner on kevlar now, otherwise little deterioration. If the burning time was assessed, I would guess a reduction would be noticable.
I also have heavy duty performance fire staff that I have been making for a similar period and supplying, some of the early examples are still eminently usable.
mark