Not being a 'tall' person myself, 6'-0". I've always wondered why some who claim to be merely an inch or two taller "require" a longer cue. I'd wager my grip hand shifts up and down roughly a foot based on necessity. If anything it stands to greater reason that a shorter player requires a longer cue. I'll just consider myself lucky I suppose.
As to playing with longer cues. I can't speak for pros or to their abilities, but I have to imagine the bulk of this length must be at the back end. I attempted to play with a shaft a mere 1" longer and couldn't do it...lol. I had gotten so used to the joint coming into my feild of veiw during my stroke, that that not having it the right spot with the longer shaft got into my head...lol. How sad am I...
I carry an extension that came with my cue purchase but very very rarely use it. It does add a few ounces at least. Simply not having my cue at the 'right' angle when attempting to chalk up is enough for me to never keep it on during play.