> In fact my own 15" MBP late 2013 has a GFX750, which is no longer supported according to Apple Support [1]
That support article doesn't mention the GFX 750 and I can't find any record of Apple selling a MBP with a GFX 750...
Edit:
I believe what you meant to say is you have a "NVIDIA GeForce GT 750M with 2GB of GDDR5 memory and automatic graphics switching" [0] which it appears does not support metal.
That support article doesn't mention the GFX 750 and I can't find any record of Apple selling a MBP with a GFX 750...
Edit:
I believe what you meant to say is you have a "NVIDIA GeForce GT 750M with 2GB of GDDR5 memory and automatic graphics switching" [0] which it appears does not support metal.
[0] https://support.apple.com/kb/sp690?locale=en_US