Donnie
Double wall drums are a feature of some high end European machines such as Probat. Randy might have switched manufacturers on the Oro as well, at least it looks so.
The guy I was helping in Chicago was a novice and wanted a 2k machine, in the end talked him into getting a 1k. I'm not a fan of the 2k size in the realm of Chinese roasters, mostly due to price vs size. For the majority of drum roaster, users roast less than full capacity with a few exceptions (mill City 1k). My thinking is the next step up from a 1k is a machine capable of roasting 5lbs of finished coffee taking into account 15% weight loss. It gives you entry into commercial accounts which can be kind of a "bread and butter" gig.
Just took a look at the Oro and there are a lot of things I like such as: precision damper vs adjustable air fan, ribbon burners, some cast iron components. The specs have some typo as well, I'd have to communicate with him to clear them up. Randy rates his machines in pounds instead of kilo's so you have to be careful there.
If you notice the front section of the drum has a cast iron hub and ring; it needs to be faced/turned on a lathe. Could end up being fairly precise; what is the gap between the faceplate and drum? Again, fancy European roasters often have this feature.