Are there any other known extension or payment method conflicts?

While Fooman Surcharge works with most other Magento extensions and payment methods, there are unlimited possible combinations and it is impossible to test them all. The ones that don't work out of the box are most often the ones that look at the individual cart items instead of charging the grand total of the order while neglecting custom totals. In most cases this can be fixed with a small code change in the payment method. Workarounds are provided for the following extensions:

• iDEAL (Dutch payment processor)
• One Step Checkout (by onestepcheckout.com)
• GoMage Light Checkout
• MultiSafepay