I appreciate your detail in describing the plant and how it grows in tropical and subtropical moist areas. Not a plant for areas where it can survive winters where there is summer moisture! I get it! However I feel that we always need to be clear when we share info to many others that it may not be a universal gardening truth! I am recently trying this concept out when I find that things I share certainly do not apply to about 90% of the rest of the country. I live in San Diego and believe me I live in the meca of microclimates! I have slowly learned the difficult lesson not to generalize about gardening...especially when it comes to the adaptation (or not) of specific plants.
I consider Ardisia crenata to be a very desirable plant for moist shade or semi-shade areas of coastal CA gardens! It is very special in that the Marlberry, as it is sometimes called,produces tiers of brilliant red berries in time for the holidays! Not only that but the crenate, almost holly-like dark green leaves fit right in! I see it as a great potted plant for many climates that are normally too cold for it where it can be brought into a sun house or indoors for part of the winter.
A great plant that is native to CA that also has great holiday display is the Toyon, or Christmasberry; Heteromeles arbutifolia. This is usually a large evergreen shrub which also has deep green nearly holly-like leaves, actually the species name comes from the similarity of its leaves to Arbutus species which have a leaf which Heteromeles seems to mimic. It produces abundant bright red clusters of berries for the winter holidays as long as it has had adequate winter rains with some summer irrigation.
Back to Ardisia...I hate cliche's but here is one that I feel is quite appropriate: "One man (woman)'s weed is another man (woman)'s rose!" I am sure your warnings have been well received! ...and thankyou again as much!
While we are at it...I wish that something could be done about the horrible bamboo-like grass Arundo donax which has taken over most of the water-shed in So CA! Millions are spent every year trying to clear water ways! Now this plant is a huge threat here! I spent a Sunday as a volunteer to clear one area of a parke along with about 30 others. I have dealt with this plant on client properties and even upon my own. Somewhere I am sure someone is enjoying its natural beauty (there is also a stunning variegated cultivar...although just as invasive here). Many people have used it as an ornamental bog or water plant.