I have them.. my opinion,
1: They are very heavy, they are plenty stout, and they weigh a lot.
2: The clamps are not very good:, they move around a lot, and will fall off
if you let them drag the ground any at all as you back out of the load.
3: I converted mine to chain on, much improved, and also added a pipe so that the bucket contact point was on more of the "meat" of the bucket lip.. you dont want the contact point way out there on the edge. At least my kubota bucket is built that way with a thick part of the metal about an inch back from the edge. But now they are even heavier than ever. But they work better, and they dont fall off.
4: I have never tried the 2x4 thing in the slots, for one thing you need to trim down a 2x4, as it is too large
to fit, and most people say the 2x4 snaps off pretty easily, I dont know, perhaps for light but bulky loads, like cardboard boxes of light stuff it would be a good thing.
5: The front end is not welded shut with sheet metal, would be easy to fix and I will get around to it. They fill with dirt and crud, pretty fast.
All that nitpicking, said, they work pretty good, (after chain on conversion) and the welds are good, and you sure get your moneys worth in metal, they are not going to fold up on you, Are they as good as a real set of Quick attach forks? no way. takes skill to use them (you cant see a thing), but for occasional use, they go on pretty quick, and they are usefull, and will pick up some pretty heavy loads,, I would not try anthing over about 7or 8 hundred pounds, tho.. I would not want to put more strain on the bucket, but I cant pickup much more than that anyway, with my loader, especially stuck out there on the front of the bucket.

my 2 cents
James K0UA