We are considering implementing SPN and are not sure of the best practice to use. We currently do backup for customers doing a combination of full and incremental backups. We also have customers doing the continuous backup.

To be most cost effective, do we need to migrate all business to a continuous backup? How is the cost/storage calculated if you do a weekly total, along with daily differentials? Our capacity cost would be based on the "sum of the total backup plus each individual defined incremental backup"?? 

We're trying to look at SPN from both a financial and best practices point of view. If anyone knows of a resource with additional information please let us know.