Should I update my Wii U if there's a chance of a power outage?

Solution 1:

You answered your own question already since you already lost a console to a power outage.

No. Seriously, don't do that.

Never update your console or any other device's firmware (system software), without a reliable power supply.

While simple software updates (apps, games, ..) are not prone to kill your console the system software is. You can always restart a game installation, but it is hard to restart a system installation if it's already dead.

Also, while it is pretty safe for your console to update games and maybe get thrown out of power it is still not recommended to update them without good power supply either. You could still break your game installation.

With an outage chance of 50% you should seriously get yourself an uninterrupted power supply (UPS) as constant outages can also damage your electrical devices even when they're not being updated.