We have an online checkout with some issues which I assume are because of the Ajax/Jquery.
For example a customer presses a button called lookup and the fields are automatically completed based on past order information, but it will tell the customer that some fields are not filled out even though they are shown as completed. A customer will have to press enter in the field.
Loading shipping methods is a problem.
In some case the checkout will complete with inaccurate shipping prices. It seems to default to US instead of the international rates.