welcome to the bandwagon paul
and it'll be a rare day when you find a lens you're happy with from now on!
what aperture setting did you shoot at.. if that's wide open at f2.8 then it's a very good result (from a highly respected lens) and you can easily afford to stop down from there. if that's already f4 or f5.6 then hard to justify exposure time to stop down further.
don't know if you have seen this timelapse work before.. this guy also uses the same lens (at least for 'learning to fly') and does amazing things with it:
http://timescapes.org/
Phil