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