eGPU with the X390 Yoga?

I purchased the X390 Yoga a few days ago with an i7-8565u, 16GB of RAM, and 512gb of storage and I'm wondering if anyone here has used it- or a similarly specced Thinkpad- with an eGPU enclosure like the Akitio Node or the Sonnet Breakaway Box. How is the experience? How would having USB ports or a second Thunderbolt port on the enclosure affect performance, especially with a 2 lane Thunderbolt 3 port? Is it possible to use the iGPU for the internal display and the eGPU for an external monitor?

EDIT: My desktop has an i7-6700 in it, 16GB of RAM, and a MSI GAMING GTX 1070. I plan to use the 1070, but am unsure if the potential performance hit that I get from moving to the Whiskey Lake i7 is worth it, especially with CPU-bound games such as Arma and Cities Skylines.