Is is really necessary to purchase SQL Backtrack?  Why would anyone pay for it if you can do same thing via RMAN?

Well for starters, SQL Backtrack does a nice job in logical extraction.  Say you want to bring back a table from a backup, you can do that with SQL Backtrack but not with RMAN.   I don't know how they do it behind the scenes but that is awesome feature.

At the same time, RMAN had the ability to find out block corruption and allows you to do incrementals as well. 

Both have their positives and negatives.   We'll see them in the points coming in newer posts.