I use both methods (visible true/false and off-canvas move slide in). Essentially it's more a question of which one you know better or are more comfortable with as they both achieve the same result in the end. There are visual effect differences though.

If you use off-canvas, it is much easier to visualize and edit a complex page as you don't have layer upon layer of graphic images to sift through. Also if you use off-canvas, you can 'slide' a panel into view creating the infamous 'sliding panel effect'. Simply adjust your x and y positioning parameters in small increments and voila!