DEBOOTSTRAP or GRML-DEBOOTSTRAP more suitable?

[Richard Owlett <rowlett@cloud85.net>]

I wish to do an _*EXTREMELY*_ minimalist install of Debian to a USB 
flash drive (aka /dev/sdb1) assuming use as a MBR device.

I currently use the i386 flavor of Stretch.
My hardware allows choosing to boot from a flash drive.

I suspect that if using deboostrap the closest I can come is using 
"--variant=minbase" which apparently installs apt. My definition of 
"minimalist" would prefer not to.

For my definitely idiosyncratic purposes *absolutely NOTHING* but grub 
related tools will _ever_ be run from this device.

What are the trade-offs of choosing between debootstrap and grml-debootstap?
I understand that either way I have some reading to do ;/

TIA