Using Paypal with Authorize.net?
I had recently looked into this for our website, so I think I can answer this question.

First, it is important to understand what this is.  It is not accepting PayPal through Authorize.net, which is what it sounds like.

What happens is you setup a PayPal account for your organization, and then you link it to your Authorize.net account.  That linking though is only for a record of transactions.  The funds collected through PayPal never make it to your Authorize.net account.  So you are left with money in your PayPal account that you still need to manage.

The only thing this is good for is consolidating records, as all of your PayPal transactions will be recorded in your Authorize.net account along with your Authorize.net transactions.

For us, that was not worth it.  If that is a benefit for you folks this sort of setup could work well.

Let me know if you have any more questions, or if you need me to clarify anything for you.