Different type of wrench

I would be afraid of the metal on metal contact. I normally even try to keep a nitrile glove or plastic bag between the OEM wrench and head/cylinder. Maybe if you find a way to line the center of the wrench with a ring of leather or something. I do like that it seems to apply an even pressure around the circumference of the cylinder.

It seems to me a good alternative tool, long before using a common clamp, as the photo of an original Cox manual shows.
As we all know, there are cylinders without the groove inserts for OEM tools, so this may be a better option, instead of the common clamp.

Whenever you have to use a clamp, place a strip of synthetic tape or 4 mm thick leather between the cylinder and the clamp to protect the cylinder.
The big difference of a common clamp to the one that shows and shares the coxaddict here, is that the coxaddict tool exerts a uniform pressure on the whole cylinder, while a common clamp exerts a pressure basically on two supports, this can be a problem, Since you can deform the cylinder.
However in my case, I definitely prefer to make the slots of the cylinders that do not have them and, therefore, use the OEM tools, especially when it comes to holding the cylinder to remove the glow plug, which many times when wanting to remove the glow plug, the cylinder unscrews.
https://www.coxengineforum.com/t12700p50-acceleration-ring-cox-tee-dee-010#163436

I have several Cox engines with no way of removing the cylinder for lack of cutouts for a wrench. A few had mufflers and throttle sleeves and some double slit cylinders. This tool worked for me.

If it works for you thats good i still use rubber hose on those stubborn ones

Cool tool, for 17 beans and if you're doing a lot of engine work, its looks like a good thing. Would be great for Cubs and later Cox cylinders.
Remember heat is our friend and if using a wrench on exhaust ports use a bit of making tape on edge of wrench to prevent marring of cylinders.

One of the English motors (DC?) used a similar cylinder arrangement. They recommended a leather belt and dowel or something like that for loosening the cylinder. Kind of similar to the oil filter wrenches used now.

Yes heat always helps.