Some answers for you about the Canon R5:
1. Quality is the same internal vs external up to 4K60, whether HQ or not.
2. External doesn't overheat up to 4K60 (non-HQ) for at least 3 hours.
3. External does overheat at 4KHQ oversampled 24 & 30p after 75 mins.
4. There's no 4KHQ 60p.

— Gerald Undone (@GeraldUndone) July 25, 2020