As a rule of thumb cards hear at 1.7 times the distance what omni's hear at 1.0. Generally they do not have the bottom end, cards, and do not hear what is behind them very well. Omni's get the "room sound" more than cards. So, if it were me, unless I could get to the 2' and 3' high place, I would go with cards. Maybe even XY.
Good luck.