We send a lot of things out every day with both royal mail and UPS. UPS we find 99.9% of the time all goes well. I guess much of this comes down to tracking and the extra cost this can incur. Royal mail again on the whole do a good job, but we do have a few issues with them from time to time.
The latest I though I would share with you. We send lots to Ireland (you know the place quite close to the mainland UK) without problems. Small packets work out quite reasonable to send and make there way without problems. But the last one we sent had a little detour, take a look at the photos, Ireland has moved to Australia. Luckily it got sorted quite quickly and our kind customer saw the funny side, but its amazing how do you mix up Ireland (look at the address label) and Australia. And why would Australian customs open it up when its not for the country?