Axe-FX will be fine with 240. Just saying. Overvoltage isn’t that big of a risk in the US as in Europe, but even there I think Axe should handle most typical scenarios just fine. It’s theoretically possible that somebody will mess up with phases and you’ll get 380 instead of 220 (400 instead of 230, 208 instead of 120 etc.). So in Europe it will be out of safe operating bounds and whatever safety margin Axe-FX has, in the US it should handle that easily. Getting some weird stuff like double the voltage like the 240 you mention would be extremely strange and unlikely, IMO. Or maybe they don’t use three phases in the US for transmission?
The situation that caused what I dealt with was an oddity, to be sure, and had to do with a power snake used by the facility that had become worn at the connection end and caused a connection that put power on the wrong conductors. I'd be the first to say it would probably never happen to me again. My point, probably poorly stated, was that I didn't anticipate something like that happening and the power supply stopped it from damaging equipment downstream from it. In all the varieties of things that
could cause extreme power issues, the common thread is you won't have time to shut down when it happens, so having something automated to handle that is a comfort.
If there is one overarching idea for me, it is that I am paid to perform, and preventive maintenance and planning is just part of being a professional. I carry spare guitars, cords, batteries, wireless modules, mics, stands, etc... even a Flyrig5 just in case my Axe FX goes belly-up on me even though, in 6 years and hundreds of gigs, my FAS gear has failed exactly 0 times. The audience wants to hear music and not excuses, so my personal decision is to do everything I can reasonably do to make sure that happens. Power protection is just one cog in that machine. The machine has run well for 40+ years.
Likely
way more that the OP or anyone else wanted to know! Sorry for that. I agree with everyone that says the chances are minimal. The chances of failure of any gear is minimal. But I do have a spare tire in my truck. My music gear is insured, even though I've never had an instrument stolen. This is that mode of thinking for musicians. Totally good with anyone who disagrees or does otherwise.