the Etek three will have the same consistency (probably) the same harshness on paint (probably) and fire at the same speed, the weight is negligible i doubt there is even 100g worth of differernce.
what people have to remember with paintball gear is that if you plotted it on a graph of performance vs price with price along the y axis, you would get a worryingly steep curve. from bottom left to top right. all markers will shoot paint, they just make you pay extra for a tiny amount less weight, less harsh on paint and good old 'agg' rating
and the price difference becomes huge where the performance difference becomes little