General rules section 5 sates that no more than two connectors shall be used per line. This is there to allow for connections on either side of your flying wires. not sure if an additional connector at the bellcrank would fly, and would likely fall under whether the judges found it suitable. that being said, if you were to switch to solid leadouts, and button bellcracnk, you'd probably be OK.
the slide connectors you show are "allowed" by the AMA, however, the confusion comes down to the wording of the rules, and with the CD having final say. if he doesn't like them, they aren't going to be allowed. if he does, they are fine. i know people who use them, i prefer the "Hawaiian snaps" however.
burden of proof is during pull test. And, if there were a failure of the snap (any type) during a flight causing damage (insurance claim) or DQ from the contest (rules violation), you'd need to prove that you were using the correct hardware.