SQL & PL/SQL

Hello All,
Oracle 11g
I am trying to understand pro's and con's for bulk update.
I have a table contains 4-5 million rows, which are going through some business rule and based on those we are doing an update for few columns.
Also there is an special scenario where i look for duplicate row in the table so when i see a dup i mark as "U" while the first occurrence marked as "I".
Something like

TABLE A
Col1     Col2    Col3 ....... Col15
1           L       K              I
1           L       K              U
2           J       P              I
1           L       K              U

........

Now my question Is bulk update suitable on this situation because currently we have normal process (cursor with 50000 commit limit). and it take around 2 hours to complete.

Any suggestions/idea will be helpful.

Thanks!