eGPU makes no sense with SB2, since SB2 has really great GPU, and doesn't support TB3.
And I forgot, I have tested SB2 connected to external 4K monitor. Played a few clips in 4K (Vivaldi browser), fans did spin up, but I had to get my ears real close to the SB2 to hear them at all. But keep in mind that this was in office, where it's not dead silence.
But in the last few days, I really have to admit - I never heard the fan spin up once! And I do use my machine and push them. Only time I heard fans was while compiling Unity3D project (1,2GB, 3D game). I did it as a test. But even then fans were really quiet!
This thing is by far the most silent portable computer I have ever owned. More silent then any MBP, and with way better thermals.
EDIT:
Expect my review by the end of the week or so. I will try to write as many observations as I possibly can think of.