Sleep Mode

Not at all, since i made the transition to a poweruser (lol ) i always leave devices to sleep, occasionally shutting down if i wont be back for days or for updates etc.
It wont do any harm to your macbook, i would say not to leave it charging once the battery seems full or while it sleeps.

 

sleep shuts down all the components except the ram, so it is very similar to turning off the computer anyways

 

It was made to sleep ... no need to shut it down all the time.

 

I thought the same thing too. And with my old MBP I would just put it to sleep most the time while shutting it down occasionally, resulting in no noticeable issues. But with my new MBP, after using it for 8 hours one day and putting it to sleep over night, It starts acting pretty sluggish.