**All** crypto prodcuts use symmetric keys to encrypt data. RSA operations are so slow in practice that no sane person ever use them to ecnrypt/decrypt **data**. All RSA based encryption schemes use a symmetric key to encrypt the data and encrypt the symmetric key with the RSA key. The addition of an RSA operation allows to digitally sign the data and/or to safely exchange the symmetric key with a remote site.

For the typical backup restore scenario there is absolutely 0 (zero) benefit from using RSA operations (more correctly: I don't see any benefit). More precisely, there is no need sign the backup with a private key for authentication purposes, and there is no need to encrypt the encryption key with a public key for key transport/exchange purposes. Using RSA keys would simply add complexity and operational risks but would offer no additional benefits.

The only RSA key usage for a backup/restore scenario I can think of right now is if a hardware module is involved (ie. the backup operator must enter the smart-badge into the reader to open the backup file).