The gall of okoffroad is amazing! To not only copy the design, but use a cheap photochop of AT's product photo puts them in the category of the lowest of the low.
Back on track to my original question, I'm still not finding any really attractive solutions out there. The BajaRack option sort of works, perhaps with modifications. I'm not a fan of their approach to fastening the cans down though - some sort of quick release latch would be much more convenient. Scepter cans don't fit in the ARB or EE products. The AT holders are great for mounting on a trailer, on a swingout behind a vehicle, bed of a pickup etc, but they can't be put in a low profile configuration for a roof rack application.
So, looks like there is an unfulfilled market need here for a Scepter gas/water can carrier for roof rack applications. Here's a description of my ideal product:
Compatible with Scepter 20L gas and water cans (accomodate the extra little spouts on the water can)
Ability to easily strip down to a low profile configuration when not in use
Quick release latching mechanism
Ability to lock the cans in the holder
Ability to mount on a variety of popular roof racks
Any clever product designers want to take this on?
I've carefully hoarded a nice collection of the unobtainable Scepter cans only to find I don't really have a good way to carry more than the two that are on my trailer.