We use contractors who do this. We get errors with their files all the time. They use the Color Map node (not supported in 2016). When you use 2017 to "Save As 2016" it doesn't remove or convert it into something 2016 understands. So, the material breaks. We also get a Mass FX version warning, thankfully that's harmless.
Our team had to downgrade to 2016 for a gig, and the viewport is taking its sweet time when I make simple stuff like connect vertices. It has a fade in/out when making modeling operations, and it'll only fully update once I move around in the viewport. I would like it to go back the way it was if possible, where the change…