Do not change your twitter nickname. It is evil.
Changed Twitter nick piss me off. Really. Especially if it is accompanied with changing avatar. Often it takes me long time to recognise who the hell I am following. Do not get me wrong. I know my followes. But it happens sometimes I add some interesting people, who tweet quite occasionally. Moreover it takes some time to get used to new followings for me. If in that moment they totally change their nickname it relly makes a mess in my brain stream.
Honestly I quite wonder, why @twitter allows to change your nickname after time. Ok, ti happens that you get married or something. But still, you should be unique from beginning and unique you should remain.
In such case you would not have had to solve problem like if it is OK to bring your followers to your new employer if you gained your followers on the brand the old one.
Moreover, your nickname after long time of activity wouldn't be free for registration. Wouldn't it @prague_style? However it is true, that when you change your nickname you get your followers with you, but remember that your branding within twittersphere is not only via following, but often retweets, #FF and mentions make some knowledge of your twitter name around twittersphere.
Another important thing is linking. Cross the web! Very often happens that tweet are quoted, you are mentioned in blog spots, you link your own twitter in discussions. These everything gets lost.
So, do not change your twitter nickname. It is evil. (and further, mainly do not change it to worse one).

