I don't think there is a way to use TDP without RMAN, but you can use RMAN 
without TDP. We are using the RMAN and TDP here. I think it performs rather 
well. If you already have TDP, RMAN comes free with Oracle, so there  really 
shouldn't be a cost issue. RMAN does a lot of different things in the 
background when backing up the Oracle database, checks for corruption of the 
datafiles when backing them up is one. It also does not put the datafiles in 
backup mode, which creates more activity and redo of the database, so it 
actually has less overhead than the traditional method of online backups for 
oracle. 

If you need anymore info, just let me know. 

Mike Borden