Well..... it's not as dramatic as their Mars A filter. Through my 10" f/5.6 dob, using the Pentax XW 7 and Delos 6mm's, Jupiter, the non red spot side, is a brownish cast like somebody threw a handfull of dirt on the planet. And the image is only dimmed a little. The 2 equatorial belts look really brown instead of grey without filter. One polar region shows the multiple banding better, and the other has that mottled look that is more easily seen. And then right along the equator you can see the festoons easier, whereas without filter you can only see hints of something. The real dark 'barges', I think you are calling them, along the equatorial bands are really dark now.
The Delos lens had these very light reflections between my eye and the filter, kind of annoying, just had to move my head a little to get them to go away. The Pentax did not have any of these.
So is the the BPL-0125 Bandmate Planetary Filter worth the price? Hey, it's only the price of their plossls, and it does actually improve the details seen, so to me the answer is yes.