If you get the 1DX I would recommend keeping the 5D3. Both share the same auto focus system, similar menus, both full frame, similar picture quality and both are of the new Canon technology generation.
Just to clarify my reasoning being the 12fps with the 1dx,,, if a majority of my shots (i estimate 50-60%) capture the ball in frame and 3-5 feet from the batter... i believe the extra 6 fps the 1dx would benefit me by getting those shots in between the 6fps of the 5dm3... thus increasing my chances of getting bat on ball by 50%.... make sense....
and my dilemma about which body to keep with the 1dx (5dm3 or 7d) is for those times when my wife would like to shoot also... and of course having a back up when needed...
again... thanks for all the responses and ides and suggestions... Dave
Oh ya... and i have tried NUMEROUS time to try timing the shot to get the bat on ball.... but i have had not had ANY success with that method.... i am currently trying to achieve the bat on ball using 3-4 shot bursts starting at different times of when i think the batter is going to start his swing...