To add some quick observations with aptX codec enabled, I am noticing no lag whatsoever in changing tracks, volume changes or switching between audio sources i.e. iTunes, Safari and so on.
It certainly has made my experience much better than what I have had before. That in itself is more than enough for me, but as aptX is considered a hi-fi codec when it comes bluetooth streaming is an obvious plus.
But overall, smoother experience, no jerking audio and cutting off.