I know almost nothing about them, but I did learn one thing about them from experience. Get a paper shreader that cross cuts the paper as opposed to one that just shreds it up and down. I have the former type (by luck). My sister in law has the latter type and is ready to throw it away (probably has thrown it away by now).
With hers, the cut paper forms into a spaghetti that almost immediately curls back and forth and then backs up into the cutter and stops her from shredding any more paper. Her bucket is no more than one quarter full when it starts backing up to the point of stopping the motor. (She has a more powerful motor than mine, but can do much less because of this.) With a cross cut, not only is the paper shredded more finely (better for security purposes), but it falls from the cutters and the bucket has to be about three quarters full before you need to empty it.
Hope this helps.