Fokin hoe/flat cutter

Anyone here have one of these tools? I just found about them and am considering buying one. Seems like I could use it for a variety of things.

If you have one or have used one, how do you like them?

Also, do you have any recommendations as to the size/style? I see the following as options but am having a hard time actually determining what the differences between them are:

Set of 2
All Mighty
Robust
Titan
Small
Medium
Large

Any help is appreciated!

Following, as I am considering getting one as well and hoping it can take the place of a few other tools I don;t have yet.

Following as well. Was looking into these a couple of weeks ago, they look to be very versatile based on the videos I saw. Would like to get one to use on the homestead this Spring, just one size that would be the most common used. Wondering which would be the best. We wouldn't have anything tall to cut, only small property gardens.  

I still don't know the proper way to use half of my gardening tools. Learning 1 tool might be the best option for me. All Mighty sounds fun, getting them!