I have essentially a static IP (A 'dynamic' IP with a 6month lease that stays the same on renewal and follows my account regardless of where I live), but you're super fucked if for some reason your IP changes. I usually set it to the /24 I'm assigned from.

I could imagine this being quite dangerous, like being on holiday, there's a power outage, fire, ISP error, etc at home and no way to control your server.

Don't do that. I did that once and our static ip changed suddenly despite lots of money being spent on it. That was a painful day driving from London to Manchester for me to get to the console.