Informative article on Loft Sails website regarding general differences between RDM & SDM
http://www.loftsails.com/loftsails-rdm-sdm-mast-compatibility-explained.htm

I understand that KA sails now offer interchangeability throughout their range too (incl their race sails).

RDM FTW

A very nice find Brian. Thanks for that!

Those comments and recommendations gell pretty much exactly with my experiences, especially with the development of the KA Koncepts from 2009 on.

The KA Koncepts work optimally on the RDM's up to about the 6.6m size depending on sailor size and weight, but can be use with either type of mast with a switch of the Cam's. We have deliberately designed more depth in the lower sail of the smaller speed sizes with the RDM's in mind. Originally, the 4.4m Koncepts were RDM only.

I don't have much experience with the KA Race sails, but they are designed primarily for the SDM masts and their longer Cams. I know some of the team sailors have been experimenting with RDM's in the smallest 5.5m, and we tested a prototype 5.2m Race at Luderitz in 2013 on an RDM, but they are really designed for SDM.

2016 KaRace is interchangable, previous years were not. Koncepts have been for quite some time.