I'm exploring using icon only navigation for tasks/sub-nav on an education app. The interaction would provide a hover tip and also an arrow at the bottom would expand the menu to show the icon text. I've seen sites like Treehouse and Confluence use this pattern. I've attached a shot of the Confluence implementation.
I question the usability stats on this pattern because of how new it is, but I also know that we may be okay with our users having to 'learn' our site once they are paid subscribers. I'm just getting into user testing, so I am considering testing the icons to see how intuitive they are for our user base.
The other option is having small labels under the icons. I don't prefer the look of this, but I feel it may be more user friendly for first time users. I also wonder if people might be okay with hovering for info or with being able to slide out the menu to see the labels.
I've read other related posts here, but wanted to take a chance asking my own way with slightly different points. I welcome any critique on my question as I am fairly new to ux stackexchange.