It's based on the grommet for the most part. If you are using a smooth Mya grommet, the silicone will get coated in slippery shisha residue and the Nammor, being heavy, will slip out easily and may tip your hookah. If you have a hard plastic grommet, the nammor wil fit much better but will tip your hookah over easier just based on it's weight. For example, I had a 22" MZ Safari that could not hold a Nammor hose - it tipped over and it the hose also came out of the tiny hose port every time.
The tips of Nammor have gotten narrower sonce the time they came out so they fit in most hookah nowadays. One other problem i could possibly foresee would be your base grommet slipping around and your stem being tipped.