Love this, I use it on just about every site.

I noticed without the customizer you can't get to any settings for the site icon - which is used by 4.4 for the icon in the embed feature, amongst other things.

I customized the old Jetpack Site Icon Module into a standalone plugin that moves the site icon option to the general settings page.

Hopefully this helps others locate their site icon after disabling the customizer

https://wordpress.org/plugins/move-site-icon-to-settings/