I've had 3" wide pcs of purpleheart cup and 24" pcs of mahogany not cup. I think it's how well it was dried, what MC it is, what kind of tension was in the board, how you milled it. That's why it's always a good idea to mill in 2 stages, so you can see how it's going to react. I don't think a wide board has any more chance of cupping than a small one if all those factors above are par.
I find it's evident pretty quickly when I start a project if the wood will be fussy. My purpleheart little jewelry box caused me fits...while a large cherry coffeee table was stable as can be. Just the way it goes.