One thing I love doing is testing my apps in real time with the Sketch Mirroring tool. This proves difficult when designing in iPhone X dimensions when I don’t yet own an iPhone X myself. For this reason I am switching to the iPhone 8 dimensions. To make the app ideal for my phone I would have to use the iPhone 8 Plus dimensions. But as the Plus models are wider than the X model it would be very hard to then convert it back from a Plus model design to an X model in Sketch artboards.