I actually never opened a case I feel that opening a case should be a last resort, there's more decent people out there than you think and most things can be resolved fairly quickly through a few messages back and forth
I can agree on that but I also feel opening a case protects you as Buyer or a Seller and even both. Just like I don't discuss anything eBay sale related with buyers outside of eBay messages on the site. This way if push comes to shove eBay can look at our correspondence back and forth. I don't see it as giving the other person any lack of credit it's just more like proper procedure in my mind.
If I have a Buyer with an issue, I call eBay and explain everything and ask "What are my rights as a Seller in this situation?" once I understand that I decide what I want to do and how I want to move forward. I then contact the Buyer with my solution to their problem, stating "This is what I was told by eBay, if you don't care for this accord then you have every right to open a claim and let them decide the outcome of this." I find that has kept bickering down to almost zero. 90% of the time people are cool and just want what they paid for but I have experienced a few jerk offs in my time on and off eBay when it comes to buying and selling.
People complain about eBay always playing favorites with the Buyer against the Seller and I have found that is not the case and they can be just as fair when a Seller has done everything by the book.
It's good to hear you were able to work something out with the Seller, Nonnahir, that's always heart warming to hear at the conclusion of eBay transactions that go array.