I dont own any of those beauties, but from talking to people out there that own them, I gather that its all in the details. Yes, they basically are a tube that holds your batteries, nothing real mysterious. The real big difference is the thing that goes on top of the battery. That is what really affects your taste and vape quality.
Again there are many new much less expensive juice delivery systems out there, phoenix, vivi nova, great attys, etc.
The difference you are paying for is the engineering behind the beauty. These devices are made to last a lifetime without minor fixes. The stainless steel they use is the highest quality, some use surgical grade etc. If you run your fingers down any of the joints or edges they are flawless. There are many AVP of the same quality made in the US. ie; super-T manufacturing(the precise). Not sure if the Zenesis is US made.
Yes a toyota will get you to where you want to go as will the rolls royce, but its all in the engineering, though I should probably say the rolls royce owner needs a live in mechanic to keep it finely tuned to keep it going for a couple hundred years.
Its all in how you want to take the ride.