How do I modify the "Why Choose Us" verbiage in RE4

You can change the verbiage via the en_US.po file, please see http://wp.contempographicdesign.com/wp_real_estate_4/help_documentation/#translation

Just update the file > save and upload to your server.

I don't recommend this, but if you don't want to use the translation file you can hard code your new verbiage via index.php > lines 86-88