I'd love to see your choppers.The absolute maximum I could possibly imagine, with lots of trouble, is about 4-5/8. And that would be if it tapered to a point at the inside edge. According to Morso, the maximum is 4".
Because the knives are on an angle, the maximum width does depend on the height as it falls along the angle of the knives (about 45°). So, if the moulding was a square, the maximum width might be as little as about 2-1/2.
The wide one I was able to chop was tall at the back and ~1 1/4" at the lip. I was able to get extra height by lifting up on the blade "unit" while bringing each successive "bite" in. It was a real PITA and if I had to do it again I definitely would use a chop saw!
But you make do with what you have, and make what you do what you need!