Tried one past fall,In real tough bean straw it didn't do anything that I could tell. Sent it back!Have a 1440 in SE MN.Straw would tangle in front of sickle sections.
If you have access to your old chopper and it is in good shape,I think you would be happier with it.Nothing else quite does the job as efficiently and thoroughly.You just can't get the impact[tip speed and shearing action] inside the rotor cage.I'm usually running my rotor faster than I would like to try and cut the stems inside.
I built my own knife bar out of swather sickle sections to bolt on to the factory knife bar for a factory chopper. It worked fine but I had a lot of trouble breaking sections out. I now use a Rodono Industries chopper bar and find it to be a lot stronger. It will still break knives in tough flax straw or if you put rebar or auger fingers through. (don't ask). The bar is about $400 cdn.
For beans I like mine fine..like all things on a combine,each change is a compromise somewhere else..Material is not as fine as a chopper will do but since it is shredded as well as cut it decomposes well...feel like the grate shredder is less and easier maintenance then the chopper is..from comments read on this board the shredder does not perform as well behind keystock grates
We tried one in our combine. We took it out and returned it. The grate would always have straw hung up in it hanging down dangling from it. We cut alot of wet wheat with tough straw and I couldn't say that it did anything but create problems. If I was buying a new chopper I would try a different one it is made more like a John Deere with swinging hammers. ButI cann't tell you who makes it. We have a Factory chopper in one of our combines and feel it could work better then it does when you hit tough straw.
I sold some shredder grates last fall and had good results, one owner did have a terrible time but found the sections were install backwards. Turned sections around and put grate in center position, he was very happy.