I have the understanding that isobaric and push-pull are two completely different things. You can have push-pull drivers mounted on the same face of the cabinet, even. Isobaric builds require a very tight sealed chamber between the drivers, and the drivers can be in the same orientation or clamshell… but the key is that the space between them is sealed. Dual-opposed is just two drivers firing outwards, but rather than being on a single front baffle, they are on opposite sides.