it occurs to me that the lines you deleted could have been for necessary
(or useful) repositories, so that rather than deleting them it would have been
better to have replaced them with the correct (lucid) versions? If that were the
case all would seem well, but you could be missing important upgrades because
your system won't know they are available.

I'm not sure if this is a real worry, nor what the precise solution is if it is
a problem, but you might want to follow it up a bit more and make sure you're
not missing out on anything.