Hi Manuel,
This plugin is not new, it was there in previous Joomla versions too. However, I see that they have added some of the options that Route 66 introduced in the past (trailing slash and redirects).
We recommend to leave those settings to their defaults. The first one is only required if your site is served in multiple domains. The second one is only used when you have configured a suffix for your URLs in Joomla global configuration. The setting that you can try to enable is the last one, but we recommend to test your site after doing that.
Let me know if you face any issues when combining those settings with Route 66.
Regards