As your original post stated----"a very capable SxS double in a short barreled hard hitting combo of 500NE or .577NE and 12GA 3" mag", ...I think it would be great.

I like the COMBO idea. Flanged big bore on one side and 12 gauge 3 inch mag on the other.

If I was in dangerous game land, hunting them or following up on them I would still load the 12 bore side with a DG hardened and heavy and high velocity slug, and not use pellets. In my humble opinion, the new DG slugs are incredibly fierce killers and I would feel confident in hunting DG game with them, having the 500NE or 577NE in the other barrel is great too. I would be confident with both or either, is all I am saying. It is sorta like: if you ONLY trust a 577/500 and do NOT trust the 12 GA 3" Mag then it makes no sense to have the 12 GA 3" in one of the barrels at all. It appears some guys do not have any faith in the modern DG magnum loaded slugs, so they are pissing on your idea. I think you do have to have experience with the DG slugs like the Brenneke 3" Black Magic Magnum, or another big DG slug, before you begin to like them...

Moreover, your price of under $3,000 is very appealing. I would want to see the craftsmanship, and learn more about the approach you're using and I need to have warm fuzzies about the reliability, however, I would give you guys an order for one of these combo guns if I liked the rest of the info from you.

Go for it!