If your complaint about the Blackmagic eGPU being “subpar” was the power of the Radeon Pro 580, you’ll be happy to hear that one with a Vega 56 is now available:
It was partially the 580, partially the inability to swap out the card. It's nice that they're offering Vega options now, but for that model I'd be paying a $500 premium over a comparable setup, with TB3 out being the only benefit. I'll stick with my Dell P2415Q + Akitio Node for now.