The stem on the X1 is short. My estimate would be 40mm, but the bars on the X1 are around 780mm, which is very wide. Wide = stable, so honestly I don't even notice the short stem.
You can use whatever stem length you prefer though. It's all down to how you want the steering to feel. A longer stem increases the bar's steering radius. It doesn't have the same effect as rake and trail. If you want to copy the X1, go for something in the 40mm range.