I am curious if you've ever actually called PayPal. I have received nothing but high quality support from them. You can call them throughout most of the working day (until 8pm PST, I believe), and they seem to have somewhat knowledgable engineers available at that tech tier. They also have a merchant technical support site that seemingly no one knows about where you can often get answers in the middle of the night (I often get responses back at 12:30). If you are even reasonably sized you can also ask for a dedicated account manager: I have the cell phone number of someone at PayPal whose job it is to find me answers to problems I have.
Though, I cannot say PayPal is perfect. I have run into a bunch of annoying issues correlating settlements (bugs filed recently, will be curious to see if they get fixed), and their pricing is not the best that is out there (although is still better than Stripe). I am curious if you've looked into any alternatives. I've spent the last few days talking to Litle & Co, and I must say that the people there /love/ talking to you about payments... their booth at ad:tech was the most enjoyable conversation I've had about payments in a while, and I got to spend another half hour on the phone with them yesterday learning more about how bank ACH settlement works.
Edit to reflect your edit ;P
That is the page I just had gone and reviewed now. It still seems incredibly manual. I would not feel comfortable running a site at scale where I'm dealing with receiving e-mails in an undocumented (probably designed-for-humans) format as my only source of notifications for chargebacks. :(
It is often these "at scale" issues that are seemingly not handled by them; example: per their API page, Stripe does not resend webhooks if there is an error in the response... doesn't this make them useless to rely on? Am I required to sit around and poll my transactions to feel 100% certain that I didn't miss something because my load balancer accidentally gave them a 503 during some traffic spike? :(