In production it definitely should be set to _false_.  If it's set to true, then payments will not go through the settlement process, and thus it is impossible to test refunds.  We're still hitting their test/staging API, so the transactions are not real.  But setting authnetTestMode = _false_ lets us simulate what a real transaction will look like start to finish.

On the flip side, we could hit authnet's production API with authnetTestMode = true, and transactions would not be settled as a way to do some testing against their prod environment, if we need to do so.