John

Welcome to NitroExpress.com. Hope you enjoy it here.

If I could afford a double in preference to a single shot I would go for the double.

If you already have a bolt action .416 you have a useful larger bore bolt action. A double in .470 or .500 would go nice with it.

I understand Mickey's comments on re-sale value and I bought my Jeffrey for that reason - as the price differential wasn't enough to loose the potential re-sale value. However I would have no problem buying a Merkel or Krieghoff if I liked one. I don't really buy and sell and plan for my grandkids to use my double(s) one day. (note the intended plural

)

As for your questions:
1.) Not qualified to answer
2.) My opinion is I would go for a double, because I would like it more and actually use it more than a single shot. I would only take a single shot .500 NE to Africa if I didn't have a big bore double.
3.) Yes I will use min in Africa (didn't have one when I last was there) and will use it on a lot of other game before I am dead.

Have fun.