This is very cool, and I wish we had something like this, but I don't see many law firms going for it.
Most law firms (and I would guess all major ones) will not allow uploading of client documents or work-product to any cloud provider, let alone an unproven start up. This risk is frankly way too high.
The only way I see this happening in the legal context is if it can be run from the firm's servers with all data hosted locally.