It gets hot under full load but the only component working outside recommended temperature range is the second M.2 (hidden) on the back of the motherboard where I stuck an old Patriot Hellfire. Its gets to 82C but is still working perfectly as far as I can tell. Its recommended range of operation is 0c to 70C. A low profile M.2 heat sink might be an option. An extra power lead was needed to power the second case fan directly from the PSU. The mobo has no internal USB 3.0 gen 2 port, just a back panel port! Being ITX it was best to attach everything possible before situating the mobo in the case. A certain amount of rearranging the Cryorig cooler's mounting brackets was necessary. Very pleased all up. Win 10 Pro installed from USB in about 2 minutes via USB 3.0. It was almost quicker than updating the BIOS. The GPU temps I listed are best guesses based on touching the heat sink. Other numbers come from the Gigabyte software that comes with the mobo.
update (3rd Jan 2020): Barrowch m.2 heatsink cannot be fitted due to insufficient clearance in the NZXT's back panel access window. case.