Hi,
what Klaus descriped is the upcoming S4/HANA programming model. It's more than just creating a BO around a table to provide transactional behaviour.
If you are currently not on NetWeaver 7.50 you can't go this way (as Klaus already explained). But going with BOPF is the right way. If you look at your business cases, you will almost never write directly back into a database table without several consistency checks. You have to deal with depencies and so on.
So reading from the database via CDS is a good idea (performance). To write your changes back (CUD), you have to provide an access layer. And this is the point where BOPF comes into place. You do not need to think about it anymore. BOPF takes care about lifecycle and transaction management.
Unfortunately BOPF is only available in the business suite foundation running NW < 7.50.
Best
Daniel