The general consensus is that if you start posting with your shortened nickname you'll confuse people and they won't recognise you. Someone clever explained that people shorten your name out of friendliness. If you do it for them it stumps them a bit. I haven't used Twinkle yet for this reason(and probably won't actually). So I wouldn't worry if the name's gone.
I did try to change to Lyra but someone's already got it. I haven't seen another Lyra about though so maybe it's someone who doesn't come on MN anymore. I have seen a Lyra41, which could lead to confusion.
I want to shorten it because the Belacqua bit is a bit of a mouthful.
Oggs, if you want to change your name, try being oggsfrogaka[insertnewnamehere] for a while then after a few weeks drop the first bit. What does your name mean btw?