On a 2024 Naish GTW-construction SUP, should one use an Epoxy or Polyester repair kit (ie. Suncure offers them in both types) for a ding repair? Thanks!

Epoxy.

Basically, always use epoxy. Epoxy works with everything and is inherently a glue, unlike polyester.

The only disadvantage of epoxy is that it is more technical to sand for large surfaces, but not an issue for ding repairs.

Sorry I am going to be rude
If you have to ask - how big is the repair and where etc?

I didn't want to truly, but I do see some horrid mistakes come into work from first time repairs...