just keep the size small, i export a medium rez under 1000 pixels usually 650. i also turn off downloading so anyone really wanting it has to try harder for 5 seconds to either screen cap it or open in a new window the image only. but the online file is small. and anything you pretty much gave your rights too you can't do anything about anyway.
without the watermark your hoards of fans can really appreciate your awesome work.
You're right, it's their problem, after all I just simply removed the watermark. This is 1024 x 768 or something like that, and even if you screengrabbed it, or downloaded it, you can hardly make a quality poster out of it, so here it is.
Thanks Aaron (btw, cool stuff on your page, as usual)