A few weeks ago I went back to all text ads after running with text/image ads for quite a long time. It didn't make much difference. 99% of my clicks are on text ads and very few people click on image ads. A while ago I tested both options and CTR was lower with text/image but EPC was higher.
When I just logged in, there was a new panel. G is now recommending that I turn specific ads to text/image from text only. There is even a prediction for how much G thinks my revenue will increase each week.
There is a button on the recommendation that makes the change automatically. Who am I to argue with Google? I have followed their recommendations and turned two ads back to text/image. No doubt, more Google recommendations will follow to turn other ads back to text/image.