Hi dastur,
I’m not quite clear on what you are considering but probably neither one. If you are considering sleeping on a latex core with separate comfort layers on top of it (which would be a completely different mattress) then the new latex core would replace the air chamber. If you put the core and the comfort layers over the air chamber then any dips or sagging in the air chamber could still come through the mattress to the sleeping surface. Both a latex mattress and an airbed generally do best with a firm non flexible support system underneath it. Plywood can certainly be firm and non flexible enough but it doesn’t provide any ventilation under the mattress so I would tend to prefer a more breathable support system unless there was a “compelling reason” to choose otherwise (see post #10 here) although it could still be an improvement .
If you are only considering a new latex comfort layer (vs a support core) to go with the comfort layers you already have then it may be a little thin to be used by itself on plywood (or any other firm non flexible base) and you may “bottom out” so you would probably need to use it on top of your air chamber to see if it helps solve the issue in combination with removing the quilted top (and it would likely be an improvement) although once again any sagging in a support system can still “come through” to the top sleeping surface.
Phoenix