Okay Craig, i just think it's kinda funny that i can post someone else's pictures and not my own.
If that was the picture he was trying to show, then it is not a N. truncata (he labeled it that didn't he?). Maybe a truncata x ventricosa hybrid? Or possibly just a form i haven't seen yet, if it has heart shaped leaves then it is at least a hybrid of truncata, but i think they don't retain that shape when they get older. I'm pretty sure there is truncata in it though.