... I use
BIOS/MBR because it is the lowest common denominator and I can move
system drives between machines of varying age.
That'll probably stop working past a certain point, at least for some
machines. On recent Intel chipsets, Dell has stopped supporting booting
from internal hard drives except in UEFI/GPT mode (as in, they no longer
offer a setting for it, and their boot-device selection menus won't let
you do it), and I gather that Intel's newer chipsets are going to stop
including support for the UEFI components that permit MBR-based boot in
the relatively-near future (if they haven't in fact done that already).
At which point you'll need to maintain two categories of system drives:
ones which can work on older machines, prior to that dropping of
support, and ones which can work on newer machines, subsequent to the
addition of UEFI/GPT booting.
Isn't progress fun?