Don't worry because I think they already know that. They made their research first before they use a thing that they are not familiar with because no one will like to put their business at risk. The op didn't mention that he has an issue about bitcoin's volatility but he said he can save more money using bitcoin. In terms of saving money, he can do that better if he will use a much stable currency or stable coins, if he don't want to use a bank again.
I think step by step when accepting bitcoin as legal currency payment transaction will give change for our costumer make research what is bitcoin and how to use bitcoin. Exactly they will research about what advantage and disadvantage when using bitcoin as transaction payment. But most important when accepting bitcoin as payment currency give little knowledge how to use bitcoin and what kinds of wallet easy when using bitcoin as transaction.
Btc's disadvantage other than volatility is like you said, transaction are irreversible but he isn't the one here that are making payments but it was his customer and in case there is an accident like his customer pays more money for one of his product, he can always return the excess money to them.
I think when OP have give little knowledge about bitcoin and their costumer made research actually they will know disadvantage about bitcoin as transaction payment, indirectly we have give the chance for investing assets when accepting bitcoin as payment currency transaction.