Comparison of RMAN and SQL-BackTrack

I do not know of such a white paper. A Google search might find some, especially from BMC since they are creating a competing product.

Personally, when backing up my databases, I'd rather go with the product supplied by the RDBMS vendor. You will get better support that way. So I'd use RMAN over SQL-BackTrack in almost every situation. I'd have to have a pretty compelling reason why I would not use RMAN. And the cost of RMAN can't be beat -- it comes free with the database. Why pay for another package to do what RMAN does for free? Plus, you'll most likely find that RMAN has features that other vendors do not implement (such as incremental backups) or do not implement well.