The part about it being "overkill" is what I'd push back on a little. I mean yeah for one gate job a mag drill looks like a lot of tool, but once you factor in how fast it eats through plate and how it clamps itself down so you're not fighting the torque with your wrists, it stops being overkill real quick. The guys I know who do a lot of steel work all end up with one eventually, and it's usually the hand drilling that drives them there. $280 used is a solid deal too, those things hold up pretty well since there's not much to wear out besides the motor and the arbor. Maybe you got a little lucky on the price but the tool itself earning its keep on one job is just how it goes with mag drills.

Reminds me of a time ice diving in Minnesota years back. We had a guy whose regulator froze up solid at 38 feet and he started breathing off his buddy's octo while they both shot for the hole. Turns out he'd been breathing right into the second stage during the walk out and the moisture in his breath froze the whole thing. After that we all started keeping our regs in a cooler with warm water til we hit the water. Never thought about the same thing happening to a dump valve though. Saltwater plus freezing temps is a whole different animal.