I have the 1.8D and just ordered the 1.4D, have not tried the 1.8G. Every review I read said the G version had more contrast and was just a bit sharper wide open. The D version is smaller, better quality and is manufactured in Thialand. I have gotten excellent results at f2.8, but it is a tad soft wide open. the 1.4D is suppose to be sharper than both f1.8 lenses and have better Bokeh. I haven't decided yet, but I may sell the 1.8D after I compare it to the f1.4D. The f1.4G is suppose to be sharper yet and have less CA, but size and cost pushed me toward the D version again, along with it's solid construction.