It certainly is in high demand. If I had it, I certainly would not be dividing it until it was a large clump.
I had 'Nell Dean' and divided it for a club sale, keeping only two fans for myself. It never regained strength and eventually died and now I need to buy it again. Granted, the price for ND will be nowhere near MOM, so even more reason for those who do have MOM to guard it closely.
I saw MOM in a garden recently and it certainly is a cute little thing! I wouldn't give up on it just yet if it were one I really wanted.
