I am impressed. There is a place for a dependable, yet extremely simple design S x S, IMO. I have some comments, if they are appropriate.
It is admirable that you provide several options, on such a simple design, of hammer types and designs for opening. I would probably opt, sight unseen at this point, for the self-cocking "hammerless" option. How you can convert such a simple action to self cocking as easily as is described is a mystery to me, but nonetheless attractive. One reason is that I am skeptical that the openings in the top tang for the external hammers look to be an invitation for trash to enter the lockwork. Hard to see how it can be avoided, due to the location of them. As much as I like the idea of being able to instantly look at the positions of the hammers I can't get past the concern for trash getting into the works.
Will the receiver be an alloy, or steel?
Lastly, this design screams ".410" !! With 30" barrels, a dream.