My BH name is Nael just cause I wanted to spell nail differently. And the Legacy name is Appoloin from my assassin. Appoloin is the angel of destruction. My assassin's name is Sishen which is 2 words in Mandarin which would loosely mean person who carries death.

Beside what has already been mentioned the only other affect you might see from this is in gear limitations. Some gear will have a Dark or Light rating attached to it. For example on Corellia I had a light saber drop that required Light IV since I was Dark IV I could not equip this item. There are also Light and Dark vendors at your fleet, so it might be good advice to check with those vendors to see if there is anything there specifically you would like to have. Also, you can negate any light or dark points that you accumulate. The cap either way is currently 10,000. So if you have 9850 dark points and 150 light points when you get more dark points it will make you light point balance decrease until you reach 10,000. Hope this helps