mrao,
I already answered this on the Texas Forum, but I would like to add something. Last night my mother and I went to SFA to listen to the director of the arboretum give a lecture. I asked him about the Michelias that SFA has offered for sale in the past (M. figo, M. skinneria, and M. maudiae) and asked him if they were going to have any different ones in the future. He said yes they would have more types, but probably not M. alba since they aren't hardy here. He also said that this April's garden sale will have loads of Michelias for sale because he got a "grab bag" of thousands of Michelia seeds from a professor in China, and he doesn't know what all kinds of Michelia they are. I am planning on going to the sale and comparing the leaves of the ones offered to the ones I already have and buying the ones that are dissimilar.
Also,
M. alba may be the most fragrant, I don't know because I've never seen one. But I can tell you that M. figo is absolutely wonderful, you can smell it from 300 ft away. M. skinneria is an improved version of M. figo, it blooms more profusely and for a longer time and is just as fragrant. My M. maudiae's are too small to bloom, but I saw one fully grown and in full bloom at SFA last night. The flowers were like little magnolia blooms and the whole tree was wonderfully fragrant, smelling up the whole garden. Plus, these 3 types of Michellias are hardy here and once established need no supplemental water.
I think a trip to SFA would be worth it (even from DFW) if you are interested in Michelias, especially since M. maudiae is not for sale anywhere that I have ever seen except for at SFA's plant sale.
Email me if you want more information,
Carrie