Avamar was pitched to us, and after finding out our environment they backed out and told us that it's not a good match - in the environment we have very high data churn (most of the db gets replaced weekly). Avamar's advertised strength is reducing the backup via dedup, and with this pattern, the dedup does very little good.

Regardless if it's backing up the BAK, DIF, TRN, or MDF/LDF, the dedup only becomes worthwhile when the data doesn't change a lot. Since the dedup doesn't add much, they told us to stay with a straight backup (Use Quest to backup BAK & DIF compressed to disk, then a 2nd backup to offsite).