I made this switch a year ago. Quite easy to transfer.
I don't have a bunq business yet and think the price is quite high
If you want the same basic price as Knab business, you could join a Pack. Here is a topic where people share spots in a Pack:
bunq is 10ct from the first transaction, unlike Knab, which has 1000 (?) free transactions / year.
In addition, how easy is transferring?
In the bunq app you can start the switching service with the push of a button. You must then confirm the Knab environment with the app or reader. It can take a few days / weeks before it is started.
Please note: foreign direct debits are not automatically transferred. You will still have to change this manually.
I have not used MT940 since bunq . bunq has a real-time link with most packages, see https://www.bunq.com/en/business-account
Automatic monthly export (and mailing) is also possible. The options that I see in the app are PDF, CSV (comma-delimited), CSV (semicolon delimited) or MT940.