For me personally, I need the following before I can/will switch to Monzo Business Banking:
Many of my clients are older and do not use online banking, and insist on paying me by cheque. My current provide Lloyds Bank has offered CI for a while now and it has made dealing with cheques so much easier. I need Monzo to offer this before I switch.
Bank Feed Support in FreeAgent
I use FreeAgent for my business accounting which is great. They have the ability to automatically import your transactions from your bank account. Before I can switch to Monzo Business, I need the Monzo feed supported in FreeAgent. This could be achieved by Monzo working with FreeAgent directly, or via their partner Yodlee.