I've used Nason epoxy before and didn't have any problems. I've used a couple of other brands and none really stood out from the others.
I probably wouldn't use Nason color or clear for a high dollar car but I've used it successfully for more 'everyday' jobs (color only, Transtar clear). It dies not cover as well as Dupont's more expensive lines but I always seal with the same valueshade as called for if I was using Chromabase and it works fairly well.
I also use Nason for single stage jobs as that's all that is available at my supplier since they quit selling Centari.
I painted the car pictured below using Nason epoxy primer , Transtar DTM high build primer, Chromabase base coat, and Transtar High Gloss clear. (Base and clear provided by customer).
Dallas