I'm happily married, so my wife is real. I'm not really sure how to interpret waifu in my scenario. There's not like one particular fictional character I like above others. Maybe Catra from She-Ra? So, if she became real it's not really like I'd be able to pursue her since I'm married. If I turned into her that would be terrifying because I would be a cat person with ears and a tail.

If I could know who my waifu is before pushing the button I would consider it, but if I don't then there's no way. The chances of being turned into something that's not human are too high. Like what if the "true waifu of my heart" is a succubus or something? How am I gonna live in society not looking like a person? That's sort of terrifying.

Just to make the discussion more interesting and less about a weird meta analysis, let's assume my waifu is a human person. Let's assume it's a woman. I'm open to the idea of a 50% chance of turning into a woman I find very attractive. I don't really have gender dysphoria, but there are a lot of things about my body I find unattractive that really bother me.