I got a set for my bench and so far so good. I have a Sjorberg Elite Duo that I picked up super cheap, so thats about 90 lbs unloaded. The casters are rated for 100lbs each, so 400 lbs total, which should be fine once I add a cabinet underneath it plus some tools. The parts are nice quality overall, and the casters are very nice. Having priced casters recently, these ones look to be about 20-30 worth of casters alone if you were to buy them on your own.
One thing to note on my specific bench was that the vertical portion of the legs is inset by about 1/8" from the horizontal foot. Based on where the mounting holes need to go, I ended up needing to put a small shim behind the plate for the top hole. The kit comes with screws that seem to work fine, though it might be worth it to switch to bolts/nuts depending on your scenario. Also, it was easier for me to disassemble the bracket to screw it in without interference. And the instructions are simply a picture showing the height for the holes from the ground.
So far so good. It accomplishes my main issue with other caster systems in that when the wheels are disengaged they are totally out of the equation. I saw some suggestions of locking casters, but for a workbench that you don't want to move when you are pushing against it that just doesn't fly.
Note that, depending on the design and location of your bench, the feet flippers may stick out in an akward way. You might consider mounting them inside the legs rather than outside to avoid that issue.
Mark 7, Pro Planer, Jointer, Bandsaw w/Kreg, Biscuit Joiner, Belt Sander, Jig Saw, Ringmaster, DC3300, Overarm Pin Router, Incra Ultimate setup
JWBS-14 w/6" riser, RBI Hawk 226 Ultra, Bosch GSM12SD Axial Glide Dual Compound Miter Saw
-- I have parts/SPTs available, so if you are in the Seattle area and need something let me know --
damagi AT gmail DOT com