I have experience with three different machines. My friend has a rosenthaw that we have used several times. If you feed more than 2-3 stalks at at time it will kick out the feed clutch. It has a set of feed rolls that pull the stalk into the head of the shredder. I had a pre 1930 (all wood) McCormick shredder (4 roll) that had a similar feed roll system. Just playing around me or my buddies would through in a full bundle of stalks from the (10-15 stalks) and it would pull it all through and shoot out a bunch of ears. I suspect that it might have missed a few. I now have a no 4 McCormick. The rolls on it are set up more like a later model corn picker. It will pretty much take corn as fast as I can throw it in and will not miss an ear.
None of these shedders will make my 39 H pull very hard. It will make the rain cap stand up, but that is about it.
You just need to play with it and see how fast it will take it. I will bet it will take corn as fast as you can throw it in.