But ......
The reason Stainless is looks satinless is not because of the relative postion in the gavanic series, it is because the nature of its corrosion products.
Iron (or low carbon steels) corrode quickly because their oxides occupy a greater volume than the metal from which they come. When iron oxidises its oxide is bigger than the underlying crystal from which it came so the oxide gets big and spalls off - nice new shiny iron again - this corrodes - and so it oxidises, spall, new iron, oxidise spall etc etc.
On Aluminium, Chromium and others - the oxide product is less voluminous than the underlying metal. So as fresh metal is exposed to oxygen, the oxidation product seals it and so no fresh metal and no more corrosion.
Now - when a Stainless setscrew is inserted into a carbon steel captive nut the oxide coating acts as a barrier to the galvanic cell and so the electrolysis process does not get a good hold. I agee some grease also helps - I took that as a given. As there are no expansive products of corrosion your setscrew will come out easier in a couple of years than any carbon steel set screw.
I have been using SS screws in car rebuilds for a long time and, outside of the theoretical reasoning above, I know that the result is better with decent stainless.
But (again) if the application has some fretting between the two metal types, or the method of corrossion is NOT oxidisation (sulpherisation for example) - I can start agreeing with you that using two metal types is a possible cause of corrosion. The fretting rubs the protective corrosion products off and non-oxides can be bigger or transmit the corrosive products through the film.
You will note - I can bore for England.[:-]
Edit reason - you don't think I could have written that and made no spelling mistooks.