Have you tried them? I've heard about them but not sure if I've seen them in action before.
I'm currently using them and I think a lot of the Kindsoil folks are as well since that's what they (Kindsoil) recommend. I use a small inner diameter air hose to water, so I'm stuck in slow water mode by default and never ran into problems with the regular fabric pots, so haven't run into the issue to say how they help with that. I really think they would just contain and hide the water coming out the side some more than prevent it, though.