On DOP-Mii, there is an option to add trucha on an IOS (I forget which). Is it a good idea? What advantages does it give (if any)?

We don't support patching IOSes. That option in DOP-Mii will patch an IOS with the trucha bug which allows fakesigned content to be used/installed on the Wii.

So... pointless except for U__ _____rs and stuff like that? (I know they're banned here.)

Also, which IOS should I run DOP-Mii on?

I would suggest you run it on IOS36 and if it asks for AHBPROT then use that.

Ok. Thanks!