I move my easel around all the time by grabbing the large support boards I use it it, and after several hours it tires out my back, in addition to manipulating big brushes and large cotton surfaces.
The lightweight gatorfoam-board practically solves this problem. I would prefer it to have a less porous surface though, it stains easily (mine is white).
My life is a bit easier now with two of these - one in imperial size, one in half.