We would go about it by putting the whole wall into a cluster and then releasing chunks based on the impulse that is applied to them
that's pretty much the same workflow in momentum. Cluster + hitimpact arrays.
hitimpacts are the bullet collision impulses exposed to ICE via scalar arrays.
Unfortunatelly, in my opinion there are two things playing against momentum in it's current version, I can't tell you if they are bullet limitations or not, but here they are:
1) let's say we have a wall made of many bricks. If they are in a cluster, bullet treats all pieces as one unique body, thus the hitimpacts are the same for all pieces. This means that one cannot use impulse alone as a condition to break the chunks. You'll have to query for a second attribute that can be distance to collision object for example. Of course this leads to imprecisions on the simulation (which can sometimes be ignored depeding on the scene).
2) missing per island initial states. Momentum already has a nice feature that treats each polygon insland of an object as a separate rigid body (aka Deform Body). This specific "wall hit by cannon ball" scenario could be resolved without any clustering if there was a way to set sleeping mode for each island separately. As it is now, if you set a deform body init state to sleeping and hit a corner of the wall, everything falls down to the ground.
other than that, the level of control you have over your simulation with momentum+ice is unbelievably powerful. So if Helge could tackle this issues + some minor fracture bugs in the next version/update/patch it will become the best simulation solution out there.
my 2 cents.