I am going to run Byron's in my new JX.21 for the up coming race season. LOL I want to see what all the hype is about. I am sure it will be awesome. I am running O'Donnell at the moment and have nothing bad to say about it. But in order to see if there is a better out there you have to try different brands.
Back when Ty Tessman made the switch from O'Donnell to Byron's I asked him what fuel he like better. He said Byron's ran cooler so he was able to lean the motor out more and therefore get better run time (He said about 30 seconds). Now of coarse this is coming from a person who is sponsored by Byron's so take it for what it's worth. But from the feedback on these forums I can easily see it being true.
But from some people at our track that were running Werks they seemed to really like it.