The slowed-down speed to create the initial backup is the only "disadvantage" that I can see: It's much quicker to Trash & Empty than to Nuke & Pave.

But I really am not entirely sure, which is why I was asking.

Boy, that's not true. It's far faster to format than to trash everything and then empty your trash. Not even close.

Certainly true with larger numbers of files/folders being deleted.

Crummy examples, but it's sort of like …

If you want to replace the entire engine in a car it'll be faster/easier to remove it all together instead of the individual parts.

Or if you want to empty a pitcher it's faster/easier to dump the contents all at once instead of pour it out a glass at a time.

Or if you're cleaning a window it's faster/easier using a large squeegee than spot cleaning with a small cloth.

Or if you're painting a wall it's faster/easier using a large brush that covers more area at a time than doing it with a small artist brush.