>Since you ultimately grind the dried beef into a powder, is there any
>reasonusing ground beef instead of sliced, wouldn't work as well?

I see one thing. Slicing piece of meat expose less open cells to oxydation
 that occur very quickly look at the  change in color of a fresh carrot or
apple juice ) grinding is opening the cells and their content is starting to
be subject to many chemical reactions ,changing the nature of the nutrients.
So the 2 end products will be  different,  nutrition wise and taste wise.
once dried the grinding of the meat will not alter the product so much
jean-claude