I have a feeling people won't notice a meaningful difference between iGPU and dGPU for most of those tasks you listed, the Iris Pro 580 is pretty powerful. dGPu if anything could cause unwanted issues, slowdowns, crashes and what not. To be honest, I am just not really for AMD GPU's in general, if they had like GTX 1050, I would be much more willing to support the dGPU model. But not for an AMD card, especially one similar to RX 460 - I just predict people will complain about all sorts of issues.
Would be happy to be wrong.