I find it pretty durable. I’ve snapped one once in a capsize righting gone wrong and I repaired it pretty easily and sailed with it for 2+ years that way.
I’ve used 3 versions of the Arriba hotstick and own two. The fiberglass one is durable but stupid heavy. The carbon/Kevlar one I think is equally durable but much lighter. The all carbon one I’m less sure about; I snapped it but in a similar situation as I did the Nacra one.
The most durable extension I have used is a Ben Hall fixed extension. I would use it everywhere but on a spin boat in light air you need something that is quickly adjustable, which is where the Nacra comes in.
There are some other alternatives, the Hobie Wildcat carbon extension is pretty nice. There is also a gentleman that makes quality versions of the Marstrom. I think CST makes some as well.
If someone is in need I have a fiberglass Arriba I could probably part ways with.