Wideband vs Narrowband
There are a couple of advantages to Narrowband over Wideband:
1) You can put double the amount of repeaters, or stations, in a band of frequencies that uses Narrowband.
Just as an example, say you can put 100 repeater pairs in the repeater portion of the 2-meter band, currently. If you switch to Narrowband, you can pretty much double that amount to 200.
2) You won't increase your "range", BUT you will "DECREASE" your receiver signal to noise ratio! In other words, you pick up less noise.
However, the advantages of Wideband are:
1) The audio quality is much better! But that's only if your radio has a HI FI type receiver! Most two-way radios have a very limited audio frequency range (300-5000 Hz), which isn't music quality, but ok for simple voice. So basically, wideband operations has no other advantage over narrowband.