Took this variation for a spin. He seems fun! A credible H/L game with lots of safe options, tons of corner carry, decent damage, fun juggles. I dunno how managing heat works in an actual game but those missiles are pretty sweet.
This is the variation I play when I dabble with Jax. I find Hunker Down to be incredibly boring. These virtually combo-less variations (like Kotal's Totemic) as so lame to me. Grinnin' Barret feels like a mix of two of my all-time favorite characters - Dudley and TJ Combo. I'm not sure why it doesn't get more attention.
F33XXBF2MB (DASH) D12 22XXDB1 (11113) Is the most optimal I've found for the stance launch.
Also worth noting as I can't see it stated here, After gotcha 11113 Is the highest damage option he has at 100 damage, with 1111 Anything else being 91.50 (with the exception of 11114 which is 60). Also worth noting 11113 will switch sides.