Are you actually going to be growing your plumeria indoors?
I don't know about the Singapore, but my Celadine has what is considered the "classic" plumeria fragrance. A major grower in Maui told me that all plumeria fragrances are judged against the Celadine. My Celadine roots up the fastest, leafs out the quickest, and makes a superb graft stock. It is also one of my best bloomers. I don't know about being more hardy though. I force all my plumeria into dormancy in the fall and they will stay dormant, without light, soil, or water until spring. As far as I know, none of them will take heavy frosts/hard freezes, whether potted up or in the ground.
