A few years ago, my brother did a comparison between 3Fg Goex, and the equivalent sized Swiss powder( the numbering system is backwards from the American system). He used his .40 caliber target gun.
He found that an Equal Volume of Swiss powder produced several hundred more FPS in velocity than the same volume of Goex powder. SDV was lower for the Swiss, indicating it was burning more completely in his barrel than Goex was.
He then used an OP wad( Walter's Vegetable Fiber Wad) over both powder charges, and found that the Swiss powder, altho still producing more velocity than the Goex, was now less than 100 fps more than Goex produced. The goex powder was now burning More completely in his barrel. SDV was very close for the two powders.
At the time, he was buying Goex for about $12.00 per pound at a case lot price. Swiss was running over $20.00 per pound. Both cost more now.
He did some computations on his computer, and figured out that by using the OP wad, and adding a bit more powder, he could achieve the same MV, and get a SDV of velocity that was so close to what he got from the Swiss powder, that the cost savings of using Goex outweighed using Swiss powder except for important match shooting, where competitors use every possible "advantage"[ perceived or real] to win a match. Since he already had the Swiss powder he bought, he has kept it to use in those big shooting matches, ONLY.
IMHO, unless you are a target match competitor, traveling to the big shoots around the country, you probably are not going to be able to justify the higher cost of the Swiss powder, or notice any significant difference over using Goex powder.
There are a couple of websites that explain how Swiss powder is made, and compare it to Goex powder.
Basically, the carbon used in Swiss powder is more pure( fewer impurities) because they use charcoal made from Alder harvested in Easter Europe. The granule size is also different- small, and based on the metric system, than Goex powder is. And, because the Swiss use the metric system, there is a slight larger amount of Potassium Nitrate used in their powder than is used in Goex. Since PN is the active ingredient in Black Powder, and since BP burns from the outside in, the slightly small granule Swiss powder gives you more Granules per volume than a similar volume of Goex. That is how the Higher MV, and lower SDV in velocity is achieve.
The lesser amount of impurities in the carbon used in Swiss powder is simply an added plus, leaving the residue finer when Swiss powder is used, in your barrel, while allowing more "soot" to be expelled out the muzzle.
Is there an advantage to using Swiss powder over Goex? Yes.
Is the advantage worth the additional cost? Only you can answer that one. :hatsoff: