I would ask them how their system stops damp tracking across the cavity as this used to be the old problem with blown in cavity insulation.

Also ask if 'cold bridging' ie cold bridging the gap between brickwork skins will be a factor?

You should also ask how it copes with condensation and moisture in the cavity, both from a point of view of air circulation and dampness affecting the insulation over time.

TBH it's not something I use in my own construction business but those are a few potential problems I see with it and what used to happen to it when it first became available.