If a customer finds himself in the middle of a purchase and with his ecount not adequately funded, he will be routed to a secure frameset off the merchant's page to load his ecount using his credit card number. Currently, ecounts can not be automatically loaded from stored credit card numbers, which is safer for the customer, but slightly less convenient. They're secure in that only the amount in the account can be fraudulently used - and even then, they're covered by the same consumer protection that MasterCard customers receive. For C2C transactions, consumers don't have the same level of protection. Merchants will find that ecount and Webcertificates don't solve the chargeback issue for them.
Customers can initiate chargebacks against merchants after paying via their ecount.
Fees, Costs, Etc. Merchants don't have to take any special action to accept Webcertificates or ecount. They pay their regular MasterCard fees to their merchant bank on these transactions just as on MasterCard transactions. Customers can send Webcertificates without paying any premium above the amount of the gift. Users of Webcertificates or ecount can use the money in their account just like a MasterCard at any Web merchants that accept MasterCard.