I have major'd in both COS and INF. Also do dev work. Both was valuable: COS = more logic & programming, INF = more design & analyst.
You need both of them in your daily work.
If you do an Hons, you can select 4x COS, 4x INF and just "register" your project & main subject in either COS/INF.
Decide which will interest you more, are the most advantage to your further career changes, are the easiest to pass (read up on the forums on comments), and then decide.
(Not sure if I really helped - might have confused you more.)