well today i put my lancome eyeshadows in the pallete, they JUST fitted in there. with the mac e/s they leave about 1mm gap or so, but the lancome ones were just a nice tight fit. also i have put my urban decay e/s in the pallete they were the exact same size as the mac. ALSOOOO... lol i dropped my 28 neutral palette from coastal scent and i depotted the shadows and put them in mac paletts.mind u, be careful as those shadows are very soft and break very easily.
as far as NYX goes, im sorry i dont know about that as they dont sell any in the uk