I went from Gamma Rio Small plus (flexi-plus green shaft) to a Gara Odin small some years ago and had appreciably less shoulder soreness with the slightly less aggressive blade and a much more flexible shaft.
I have those same exact paddles and I got the odin small with the softest shaft. I agree 100% with how much gentler the odin is on the shoulders. But I am not sure that is due to shaft flex. I was actually surprised to find that the most flexible gara shaft was not as flexible as the shaft on my epic mid (full carbon shaft, not the newer progrip series). I would recommend considering the epic small mid in full carbon. As for the epic mid twist, a lot of people love it, but it is very different from gamma type paddles and from low twist modified teardrop paddles like the original epic or the gara odin (those latter two paddles behave very similarly in my experience). Finally, the gamma paddles have such a nice catch and exit that it is difficult to improve on that experience if it is something that really works for you. As mentioned before, paddle preference is very personal and everyone is different.
Current Skis: Nelo Vanquish AIR, NK 670 double, NK exrcize, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic v10g3, Kai Waa Vega, Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy