I went through the same thought process. The way I see it, if you're a big enough name to be reputable, then you should definitely handle payment yourself, but

I went through the same thought process. The way I see it, if you're a big enough name to be reputable, then you should definitely handle payment yourself, but if you're still trying to get traction and a reputation, leveraging PayPay's reasonably trusted record is a good way to go. For quite awhile both wordpress.com and stumblupon both were using paypal as their payment method for buying credits.