[RickS]

Can anyone comment on the performance of a newish MBP with this kit relative to a modest custom gaming PC?

[gt_]

It's fine. I've done this just with Windows on a 2014 macbook with the nvidia (I think m950) graphics card.

Developing VR involves low framerate experiences no matter what you use. I have a PC as well, but I would not hesitate to use my MBP again at all.