I have a razer naga, and i can tell you it only provides a good advantage with games like WoW cause you have 40 abilities you can use and you can easily bind them all on your naga (using alt/ctrl and shift) so you mainly focus on your deplacements while your thumbs and left pinky do all the work.
Otherwise, in games with few keybinding (like any moba) it doesn't provides you any advantage at all, unless you need to do a key combination really fast with a perfect timing, as an exemple, alistar in league of legends requires you to use ur ''w'' abilitie and from 0.40 to 0.60secs use your Q, the naga can give you a 99% success with their macros. That's right, you can set the mouse to use W, wait 0.5secs, then use Q. Which gives you an insane advantage but these kinds of things are unlikely to happen in ESO.
In ESO, the only difference will probably be than the naga user won't ever move his left hand and set all his abilities on the mouse, while the ''standard'' mouse users will have to stop deplacements from 0 to 0.5seconds to use their abilities. that's very negligible