I use storyboards for everything, at the moment I don't directly collaborate on them with designers but it does make incorporating design feedback a lot easier in my opinion. If a designer mentions that something looks off I can just push it a point in a direction and immediately show the result. After the designer thinks it looks right you can go ahead and do whatever work is necessary to make it look like that in every screen size / orientation / localization.
Three generic tips when working with storyboards.
1. Try to make the storyboard look as much like the real app as possible. Inevitable there are going to be things that can only be done in code but you can often at least make the UI familiar. That way you can still move things around and show a designer what the end result is going to look like.
2. Setup constraints as late as possible. Quickly prototyping is easier if you only have to take current screen size / localization into account. I tend to have a phase after finishing a new UI where I go through it and setup constraints.
3. Agree on naming conventions. A large part of working with storyboards from code is arbitrary strings that identify the components of your storyboards (segues, view controllers, etc). By consistently using the same names you make your life a lot easier. I
open sourced mine if you're looking for inspiration.
Hope that helps.
- Klaas Pieter