Yep...have used those too and they are okay for imaging, but your exposures will have to increase to make up for the blocking capacity of the filter itself.
Now, that being said, and after looking at the fine images from Cloudy Nights (warning: never, ever believe everything that you read on Cloudy Nights.....), you reallly cannot judge the improvement of the filter use because NO photo without the filter is presented to compare to. That is the only way to judge: 1) loss of sky contrast; 2) loss of magnitude or brightness; 3) loss of contrast.
That being said, this particularly filter is pretty good, as good as any. But you still will lose some contrast and brightness by its use.....again no such thing as somewith without giving up something else.