From what you've shown, Cycles is THE WAY FORWARD for accurate texture rendering, right?
But what would you use Internal for? I know you called it legacy, which to me means 'old and don't use' but it looks like you can use it to make accurate textures for, perhaps, stage 2 (Diffuse element, the paint layer) for your Cycles tutorial. Is that what it's for? Or can literally every stage of texturing be done through Cycles?
I wrote an article about Cycles VS Blender Internal that answers most of these questions. However it's a few years old and Blender Internal is officially removed from 2.8 and thus won't be used much (if at all) going forward.
Note that these fundamental courses will get a full update + re-record soon after 2.8 is released.
Fantastic, thank you. I was wondering as the visual fidelity you achieved in cycles was far better than what you had demonstrated in Internal. For now though, how is 2.8 different? I know the GUI is different with a lot of 'widgetry' and a few things are moving places, but is there a substantial change to the node system? I remember reading Eevee will be included as standard, so I'm looking forward to the revised lessons.
EDIT: THAT BEING SAID. Could you also show HOW you generated the normal/scratch textures for the Orbot in the revision? I personally would much prefer one solid chain of lessons that is fully inclusive of everything from blank scene to completed asset. Like the sci-fi helmet!