Do these things work? I have seen them before, and have always been curious.

Not really.
For a compensator to work well at handun pressures, they have to have an opening pretty close to bore size or too much gas will escape following the same path as the bullet rather than pass though the ports. Those bushing comps have to be cut pretty large in diameter to pass over the barrel.

The larger the caliber, the closer it will come to the comp's inside diameter, but then you get another issue- lack of pressure.
The .45 bore would come closest to the comp's I.D., but runs at a relatively low pressure.
The 9mm/.355 bore calibers run at higher pressures, but are that much smaller than the comp's I.D., allowing too much gas to blow out without doing anything.

And, a lot of people think that what makes a good compensator work is the gas pushing against it's forward vertical walls rather than "jetting" it upward through ports. Most good comps are made with "expansion chambers" that are cut to larger than bore diamter, but with walled compartments having near-bullet diameter holes for the bullet to pass through. The gasses enter, expanding in the free space, and strike against the forward walls of these compartments which tries to push the comp off the barrel. They can't, so instead, it pushes the gun away from the shooter and counteracts recoil to a (varying) degree.
The bushing comps don't have any of these expansion chamber walls to work against. I suppose the gasses can work against what thin metal there is along the front edge of it's slots, but that isn't much.

Some people will tell you they help, but if they do, it's mostly from the added weight of them hanging out there.