The Skyway checkpoint is a gamble. MOST of the time it's short. But sometimes it can be really long. The main terminal has a lot of lanes to spread people around on, but the G/C checkpoint doesn't, so if a lot of people show up at once, a line forms and the checkpoint just doesn't have the throughput to clear it.
If you're going to the C Worldclub, it might be worth it, but if you're going straight to a G1-G8 gate, the couple minutes of potential time savings probably isn't worth the risk.