It works great. It increases the chance that the model misses some details in the prompt, and the images definitely look worse, but that's what you would expect for rendering twice as fast.

I'm currently building a thumbnail catalog of thousands of images, and this is helping dramatically. Works great, slight shifts in output but barely most of the time, and sometimes these outputs beat 9-step. There are some that introduce issues you wouldn't normally have without, but for what I'm using it for it doesnt matter.