There is actually a pretty big capacity discrepancy between Rat and Mystic Manor. Rat is >2k in real world execution and Mystic Manor in the lower teens. Rat boats discrete seats, duo loading platforms and duplicated show scenes.
All of which is to say I really don't know what the Battle Escape ride will end up being. But I think
@marni1971 's stance has been mid to low teens. Unless there is loading platform duplication, show scene duplication or more than 2 vehicles dispatched, I'd expect the ride capacity to come out on the Mystic Manor side of things.
Which, reliably at least... is slightly better than original Soarin'/TSMM/Flight of Passage/SDMT. But unfortunately, just slightly.