2 weeks down the line and actual checkout abandonment is around 12% - this is from people whose cards are not signed up for VbV and who refuse to sign up at the moment of purchase. plus a further 7% whose card was signed up but they chose not to / or didn't know how to authenticate. so approx 20% total.
of this 20%, one third then went on to try a different payment method (paypal or different card) and complete the order. so in real terms we are looking at a 13.5% abandonment.
however, the secure logos have increased the % of visitors going from the cart to the checkout process by 70% and the number of visitors actually completing the checkout process by 6%. so the upshot is still a large % increase in sales (not to mention complete peace of mind).
(there has also been a slight increase in people using paypal)