The yoast one is better in my opinion. It's easy enough to try it. It won't affect your theme.
If you're afraid of that happening, just create a wordpress test site in a subdirectory and test it out there with a generic installation and see if you like it.
You can have as many wordpress sites as there is room for them on your server. If you want to see how something works, just make a new site in a new directory and check it out. That way you don't have to experiment on your live site.
You should always have one or more test sites going at the same time.
Cheers,
Ed