AMEX SDM masts have been rumored to be middle of the way with regards to bend, and some measurements, see http://www.peterman.dk/masts-all-imcs01.htm
, does support it. You mast probably has a 12-13% bend curve.
If you want to get the best out of your very good mast then
- the top is too stiff for Neil Pryde sails
- the top is too soft for Maui Sails, and probably also for Gaastra.
- A good bet is at least Severne, Simmer and Sailworks.
I think you should go about 5.3, 6.0, 7.0, 8.5. And potentially switch the 8.5 for a Severne Glide 7.5 which has about as much bottom end as a regular freerace 9.0 sail.