Gotta say that there’s a lot of Kallax in my house. There’s a reason that I built My multimedia PC for Kallax shelving.
In terms of modular organization, it’s convenient, and I can get the aesthetics past those who won’t accept brick and board shelving. (Honestly, I thought it was all too much bother and fuss for a long time.) I’m using one for a TV bench in my bedroom, (4 wide by 2 high) and it’s very stable at that height. They don’t wobble when everything is tight, and the ~16" base is more than stable enough for the ~31" height. It would take a lot of lateral load to topple it. Now it’s more a matter of uniformity. (I would probably have just chosen something a lot more utilitarian, left to my own devices. I still have a bunch of the old Sten shelving in the garage, and really wish that I could buy more of it.)
I went and picked up the Kallax units. I’m going to connect them together with a separator piece which will also attach them to the work surface.