We have just been sent some metrics that you can share with your customers:

•             PayPal has 113.2 million active registered accounts available in 190 markets and supports payments in 25 currencies.

•             PayPal expects to process $10 billion in mobile payment volume in 2012

•             31% of buyers said they would not have made the purchase if Paypal had not been offered as a payment method.

•             There was an 18% average increase in sales from merchants since adding Express Checkout

•             $3 billion in PayPal balance turns over every fortnight

As its pretty much a standard option in Magento, I can't see why it would be implemented. Plus, Paypal:

•             is a lot easier to use on mobile devices

•             it avoids the "conversion killer" that 3D payer authentication is claimed to be