I don't remember what model our Roto Grind was. We had it as long as I can remember. Like offroadnt said they are pretty simple machines. Easy to maintain and simple to use. We ran ours with a 7110 magnum and it was a good match. If I recall it would do a dry round hay bale in about 6-7 minutes and straw in 5-6 minutes. Never really pushed it to hard, and never had to change shear pins. There was, or maybe there still is an adapter to use it to grind high moisture grain. Did that a few times, but high moisture doesn't work the best for our system of feeding. You really have to watch the dust, they are really good at making a nice fine dust, that will plug air filters, rad's, cab filters, and coating everything in a really nice fine dust. It did a really nice job of chopping, it was probably a bit extravagant for our operation chopping no more than 50 hay bales and maybe 100 straw bales on years we fed straw. But in this area it was next to impossible to find a custom guy to come when you needed them, so kind of needed to be able to do it our selfs.
Now we use a highline bale processor with there feed chopper add on for chopping hay. It doesn't cut quite as nice as the Roto Grind, but it does do a nice even job, and we also use it for bedding pens, which is something we couldn't do with our Roto Grind.