I was very wary of Simple Delivery, but it is working well for me.  I have to declare the weight and size category of the item at the time of listing, then just print out the postage label from eBay.  Costs are slightly higher, but far more convenient than manually copying over the name, address, phone number and email from the eBay invoice into the Royal Mail website, then paying for the postage.  

I have also just had my first ever return request, which has been almost faultless and automated in eBay, the buyer said the item was broken in transit and sent some photos, and I instantly got a refund due to the selected delivery option including insurance. Lol, the item had actually sold for far more than I expected / it was worth so both buyer and seller are happy!

Also don't forget that until recently eBay was charging a final value fee of roughly 15% on private seller auctions, this was then dropped and subsequently the buyer protection fee and simple delivery have been added (with costs incurred, just in a different way), the only pain is that unless you are meticulous, withb the BPF added auctions all start at weird amounts!