Once you have a service that looks unlikely to go out of business or a well branded service then I see no reason why you shouldn't post backups to the cloud.
Use Truecrypt to create an encrypted container file, put your stuff in there and upload.
Truecrypt is open source which means every expert around can inspect its integrity and comment about its security. AES256 is a pretty good encryption process as long as you choose a suitable passphrase (which you can remember).
1. Dont't use John01051975 if that's your name and DOB.
2. Don't use phrases from films or songs. They are vulnerable to dictionary attacks.
3. Use something personal such that only you know it...Such as date your first......well use your imagination for that one. Date of your first ASBO etc
plus some other random personal stuff.