I'd have to go with the LS on that one since it's a click while the RB would be a press am I right?
After the click, your right index finger would be free to press turbo (RT) and push the defender after the post up sequence was initiated. Pressing RB and RT at the same time would be very uncomfortable.
But if the RB initiated back down turns out to be a click as well, then I guess we're fine either way since the right index finger becomes free after the click as well.