So the gen 1 Rocket has the conventional set up and the gen 2 has the t-plane? Might explain why the new Rocket is a bit more buzzy in lower RPM and why the firing order was changed from 1-2-3 to 1-3-2?
I believe triples can be either 1-2-3 or 1-3-2, with a normal 120° crank.
This video shows the 'old' Rocket III (which appears to have the same crank config as the 'new' Rocket 3) pistons moving down in the order of 1-3-2, yet it has a 1-2-3 firing order.