Ok, so from what I have compared between Mac and Windows builds of Blender 2.8 there is some discrepancy: not everything works as well in the viewport on Mac as soon as Eevee is being used.
If booting into a Windows install via Bootcamp is an option for you then I’m sure for Blender you’ll get more out of the hardware. Should be pretty good then, pending quality of AMD GPU drivers (which I have no clue about).
I’m using mid 2012 15" retina MBP, with 2.7GHz 4 core CPU + Intel HD4000 graphics (i7-3820QM), 16GB RAM.
My subjective opinion regarding viewport performance (in solid view):
I can move around and manipulate any objects smoothly up to around 1.6M tris scene in solid view. Switching to look dev, it took around 40 seconds for shaders compilation. Look dev is stuttery but still usable as a way to see UV mapping. I wouldn’t go any higher tris in look dev mode.
Around 2.5M tris there’s slight stutter but it’s alright most of the time.
Around 6M tris it’s stuttering most of the time.
Around 8M tris it’s not feasible to do any work, except to see the final results.
I expect you would have better results in 16" MBP.
I usually render in desktop so I cannot comment on MBP performance. Also haven’t tried AMD Pro Render.