I'm a left eye cross-dominant as well. When I took up shotgun, everything I read suggested go lefty, so I did. With pistol I've never considered it. I always practice some holding left, but I've never tried to compare accuracy or trigger control?
Your right brain deals with creativity, imagination, intuition, 3-D forms and your left hand. . . so maybe the signal is better?
I don't know the rules but it seems like it would be easier to hold left when moving left or shooting around an obstacle on your right and holding right moving right. . .
also for reloading. Seems awkward to hold right, run left while pointing down range and reloading.