The focus of system dynamics is to build capacity in areas that hinder learning.
What hinders learning?
I am an advocate for letting participants touch the model. It allows each of them to have their own personal experience. That being said, I would make sure that when you show them the model navigation you also more how to think about things. You should give an example and explain the graphs and why it happens. And use an example with Dynamic complexity of some sort. You should also make sure that there are enough facilitators to answer questions, because they won't be able to figure out why something that surprises them happens. You should also have a strong debrief in which you consolidate the group strategy and explain some of its strengths and areas for improvement.
Also, I would be careful about limiting the number of sliders overall. They will need many sliders to get to below 2 degrees temperature increase. And it is the interrelations between the choices that get a little interesting (e.g. electrification is stronger after we have cleaned the grid). Pulling one lever at a time doesn't give the full picture.