I paddle a Jantex Gamma medium. An experienced K1 paddler in our club told me after trying my paddle, that it's the same shape as his Braca XI. Didn't try myself, but no reason to doubt him.
I learned to paddle with a Braca IV max and respect that paddle a lot. I can make some comparisons between the two:
1) Gamma/BracaXI has a firmer catch. Like a member of this forum once said, it's like setting the paddle in concrete. It will hope You a lot in rough water, because You can use it as a stability pole - just hit the blade into the water and hold on to it
So I would definitely prefer it for surf skiing in textured water.
2) G/XI is on the one hand forgiving at the catch, but is much more cruel if You don't pull the blade away from You in the pull phase. If You try pulling it close to the boat, especially if Your boat is unstable, You will capsize!
3) I know it's not ideal to compare a Gamma medium to Braca IV max, but a major difference between these two is among other things the cadence. Gamma is a high stroke rate paddle. It's much easier to pull through water and the exit is super clean and fast, so to paddle faster You will have to increase strokes per minute. I personally hate that part, when I try to sprint, because my fitness level lacks the endurance to increase the stroke rate. I would rather pull hard on a larger blade with a quiter tempo.
4) Bracing is better with the Gamma/XI than IV, because it doesn't sink
It's hard to explain but for me it's much harder to press the medium Gamma under water than a max IV. So again, if You tend to brace a lot, Gamma/XI is the way to go.
5) Varying force through the stroke. Gamma/XI is not so straight forward during the catch/pull/exit phases. In my view it goes like this: a) super-solid catch; b) initially a bit lighter pull in the first 1/3 of the pull phase; c) then get a bit heavier in the other 2/3; d) super easy exit. It takes a bit of getting used to, but nothing too hard:)
In conclusion, I would say that the Gamma/XI is by far my preferred paddle from the two for surf ski. I am currently thinking about buying a second paddle with larger blades for flatter days and maybe double surf ski, which will allow me to apply more power for shorter distances. I will try to understand other paddles as well, but think there is a good chance I will go with another Gamma at larger blade size.