Being able to trap the ejected shells in your hand is wholely dependent on the way the gun is held when opening. It is no issue for myself, but I know some who have a hard time with it.
I have seen several of the trap shootets who catch the ejected shells in mid air with ease, and so fast that it boggles the mind to watch it. Has anyone seen someone catch the shells ejected from a SxS? I feel like the geometry of a O/U makes it easier since the shells are shot out in a more upright direction vs. the direction of over the shoulder as a SxS would.