According to another forum, you get about .6gr more powder and 75fps over the 6x45.
From the designer, instead of 5.56 brass, it is necked down 350 legend, so a rebated rim and more steps to form brass. They only pressure tested to 55k psi. They claim 5gr more water capacity over the 6x45 and coal of 2.30” and achieve 6arc performance.
The numbers I saw posted were regarding an 87gr Berger going 3010fps from a 24” barrel. I have an accurate load with the 87 vmax at 2690 from a 16” but I had it up to 2820 iirc when I saw pressure signs. So kind of a Granny Smith vs golden delicious comparison.
I would be slightly concerned with a sticky bolt, where I know (my sample of one) 6x45 doesn’t have an issue.