I couldn't have installed Debian Stretch on my new laptop ( HP Probook 430 g4 ) from USB drive ( configured on another debian machine with commands:
# cp debian.iso /dev/sdX
# sync
) - the screen were going blank and black after the installation mode selection menu.
I had AHCI enabled and Secure Boot disabled. After a couple times of trials with different boot settings - messing with acpi=off nomodeset etc. in the boot options - I gave up and installed Debian with UEFI set to Legacy Support compabillity. In the Debian installation manual it is written that the Debian automatically install the variation of system that is compatible with current MoBo settings - so with UEFI with legacy support in my case.
Provided the new system uses GTP partitioning anyway ( checked it ), instead of outdated MBR, are there any other performance / security / stability etc. features that native-UEFI-compatible Debian OS would posses - contrary to its UEFI-with-legacy-mode-compatible version?
Anything that could persuade me to keep trying to install Debian on native - Uefi - set laptop?

As far as I know, the chief advantages for the end user are that you can have a hard drive of over 2 terabytes and more than 4 primary partitions. If those restrictions affect you, then UEFI is the way to go. Presumably legacy BIOS will eventually disappear from motherboards, but I wouldn't hold your breath!