Drilled or External Overflow?

[GMGQ]

Drilled = 100% flood safe
External Overflow = Not 100% flood safe

Valid arguments for both, they both can fail if clogged obviously.

But the External Overflow can also fail if it loses it's syphon when trying to restart after a power outtage.

I regret having an external overflow, it's a constant fear of flooding (happened a few times). I wont make that mistake for the next tank.

Regarding the sump, you would want a sump from the start. That's where you keep all the equipment (protein skimmer, heater, filter socks, media reactor, maybe a section for chaeto, etc.).