I recently purchased an item on Amazon that I needed delivered quickly, so I selected Express delivery from the delivery options. I saw a message - did I want to spend £49 and get express delivery on all my orders for a year? I decided against it - most of the time I can live with the delay of supersaver delivery. On the same day, I bought a load of stuff with free delivery.
You may see where this is going - yes, the free delivery stuff arrived yesterday, without a hitch. The doorbell is in need of batteries, so I didn't hear it arrive. No problem - the Postie left it in my Parcelsafe. The express delivery stuff shipped yesterday, and was attempted delivery today. I'd popped into town with Nathan at the time. Thing is, Express delivery requires a signature, and my Postie wouldn't leave it in the Parcelsafe and has had to take it back to the depot. And if you've ever done a big trip into town with a nearly-2-year-old, you'll understand my reluctance to venture back again this afternoon!
So yeah, stick with free delivery - most of the time it works out fine.