Everyone (or pretty much everyone) on this forum talks as if the charcoal canister is the spawn of Lucifer and its removal (the equivalent of an exorcism) is essential for better luck while riding. Or more commonly it's ugly, and since we all know ugly slows you down ... for some reason ... get that bastard out of there!
Hold on just a minute!
It serves a couple functions that are if not essential, then very useful.
First, it traps and holds evaporitive emissions from the fuel tank, then reintroduces the hydrocarbons back into the intake tract to be used to produce power. The ECU compensates for the extra Hc by altering the injection duration very slightly.
Second, it is an excellent barrier against water entering the tank via the atmosphere or during a heavy rain: very useful in humid or rainy climates. You're on your own at gas stations.
A minor third advantage is the filler cap is not vented. "So what!" I hear many say. The "what" is a matter of safety. Many times when racing, especially when the tank is closer to empty than full, a sudden maneuver will slosh the fuel, and a stream of vapors will emit from the cap ... right into your helmet if you are in a tuck. Not very pleasant, and distracting if it makes your eyes water, as it has to me a few times. Additionally, a friend dropped by for a visit in the morning, placed her helmet on the tank over the cap, and the fumes from the warming air / fuel in the tank attacked the EPS foam liner of the helmet. When she went to put it on several hours later it had gained about a size and a half, and, of course, it smelled gawdawful. Scratch one very expensive helmet.
One last point -- it weighs, what? A pound and a half or so? Whoopee, and since the weight is carried below the CG of the bike it lowers the polar moment a tiny amount, resulting in an infinitesimally quicker turn in to corners. Did I mention it was a tiny difference? Good.
My advice? Leave it where it is and know you're being environmentally conscious while having fun / running an errand / whatever.