I think the laugh track influences more than just the audio aspect of a show, it influences how they shoot the show and how they edit it as well. I think it influences the acting too. Generally sitcoms with laugh tracks are also multi-camera set ups with obviously artificial sets.

Shows like Arrested Development, Modern Family, The Office, 30 Rock, all without laugh tracks, all are single camera shows. The acting on shows with laugh tracks tend to be more exaggerated and prolonged, probably because there needs to be some sort of canvas on which the laugh track has to be played over. The laugh track shows also don't have the benefit of interesting camera angles, cuts, and edits since that would disrupt the laugh track as well. It's very streamlined. Camera is facing the actors, actors say something funny, they hold their facial expressions as the laugh track plays, and then continue. And there's not much chance for subtle in humor.

One of the things I really enjoy about shows like The Office, AD, & Modern Family are the scenes where the camera is "hidden" or quietly taking in someone's reaction or juxtaposing what someone is saying with a scene that is playing out somewhere else. Laugh track shows never do this. They can't play around as much, there's not much room for fluidity or different story telling techniques. And there's not much of a chance that there will be subtlety in the humor. I love the quick as lightening play on words that happens on shows like Glee that you just might miss if you don't pay attention or the humor has depth to it where it's funny at first and then funnier even more when you think about it. On laugh track shows, there is a joke, and then there is laughter. Nothing more and nothing less.

That doesn't make the jokes any less funny, just much MUCH less subtle.