I know a lot of people are going to have an issue with this but...
I'm a 'Northerner' but I don't accept the legitimacy of Somaliland as a separate state to Somalia (and btw neither does the rest of the world) and I'll tell you why.
In terms of culture, language, religion and even ethnicity they're the same. The only reason that some Northerners and Southerners want it separate is because after Said Barre was kicked out the turmoil that followed had left much of the North at peace. Most people in Mogadishu now fled to Hergesa because it's safer.
We're already divided as a Muslim Ummah, it would be lovely to see as one again; so why on earth would you want to further divide a Muslim country that not only shares values and religion, but language, culture, history and ethnicity as well?
There is no valid reason...Somalia was one once a upon a time, then came the European colonizers. They separated Somalia to the Italian Somaliland, British Somaliland & Ogaden and the French Djibouti because they all wanted a little piece of Africa and it's people. They left what was originally Greater Somalia into 3 countries and you want to divide it further? Why?