Thanks for the interest.
Mirex is the original maker that came up with this design. They've partnered with HCam to come out with the newest versions.
Few things to know to make your decisions.
With the newer versions (I have one here), they've modified the shape of a mask (from circular to square-ish), which gives you an extra couple mm of shifting in certain directions before vignetting. Using my TS-E 17 here's the comparison. TS is total shift, in parentheses are how much shifting is done on the lens, then on the adapter:
Mirex Version
Horizontal: TS = 18mm (6 + 12)
Vertical: TS = 20 (8 + 12)
HCam Version
Horitonzal: TS =19 (7 + 12)
Vertical: TS = 20 (8 + 12)
In all cases you want to shift maximally on the lens first then on the adapter for maximum movements when combining with a TS lens (which is my main purpose). With the 17-40F4L that I have, the image circle is minimum at 17mm and increases till around 20mm and stays the same thereafter. Here are the number of maximum shift horizontally with the two adapters:
Mirex: 2mm, 6mm
HCam: 2mm, 9mm
So the shape of the mask does contribute to ~2-3mm of additional shift in certain directions.
Personally, the reason to get the HCam version is not the extra 2mm in certain directions though; it's rather the collar that allows for easy rotation of the assembly (the collar has a tripod bracket so you can quickly swap between landscape and portrait). But do know that they've also increased the price. You would be paying about twice what I'm asking for for the new HCam version. Another downside is bulk; the new HCam version is gigantic
Version II will NOT let you mount on a Canon body for the simple reason that you can't add an adapter between a Canon lens and a Canon body and still get infinity focus. This thing only works because you mount on a Sony E mount, with much shorter flange focal distance.
Now, Mirex *does* make their TS adapters for Medium Format to Canon EF bodies; e.g., I have one that does Mamiya 645 -> Canon EF. I have no idea if they're planning an HCam version of those.
Personally, I think my offer is a good bargain; if I were to choose to buy one of these for myself, I'd buy the older version for half the price. The reason I'm getting rid of that one is because I already have the HCam version, and the easy rotation mechanism is nice
Let me know if you're interested!