I only sail RDMs from 340 to 460 and I will not go back to SDM any time soon. Hot Sails Maui uses RDMs on their whole line and I am very happy with the bulletproof performance of the HOT RODS, from my Superfreak UL all the way to my race sails GPS. I actually love the fact that I can use the same mast on a Wave sail and on a Race Sail.
In general I think the consensus is that RDM are way stronger than SDM, and it is really a no brainer which one to choose in the waves or B&J. For the same carbon content they are indeed somewhat heavier, but keep in mind that a 90-100% carbon SDM is a big durability question mark, while a 90-100% RDM will probably outlast you. You should really compare a 75% SDM with a 90-100% RDM for durability (again not in the waves/B&J), and then the weight is the same. They are, in addition, easier to handle out and in the water (and easier to carry around, no need of a hard case, can be stored flat on top of each other, only one type of extension ... I saved a quite a lot of space in my van when I switched).
In terms of performance you need to rig a sail (more or less) on the mast it has been designed for, and if a mast feel too soft with a lot of extension for a 105Kg it just means ... it is the wrong mast for the application. Or if you use a race sail designed around a SDM you would be badly served by a RDM, and if you are a heavyweight a SDM + racesail is probably still the way to go, if you race. Same for big slalom sails (>8.5) or formula. For availability: Hot Sails has 92 and 97% carbon RDM in the lineup from 310 to 490 (65% carbon 340 to 430), and Loft Sails has a 520 in production.
I personally wish RDMs were the industry standard: this sport can use some simplification!
Last edited by davide; 3rd June 2011 at 10:51 PM.