I successfully used a 2011Naish drop shape SDM 90%carbon in my loft blades 6.3 and 7.0 previously. I now use Loft RDM's though as had too many SDM breakages. Can't see that it'd be a problem although if you have the chance to rig the sail with it before you buy, then do so.
Thanks Sausage, I'd already checked the mast selector and noted that they were reasonably but not 100% compatable. Have you noticed any difference in cam roatation or sail performance now that you are using the Loft RDM? What is a Loft RDM mast worth?
John, Cam rotation is excellent with the rdm opposed to an SDM. I had used sdm's for a long time until only recently and am still getting my head around how the sail feels different when pumping onto the plane or when a gust hits. Much softer feel with them so acceleration not as sudden but no difference at top speed. Sail seems to set much deeper with the rdm too. Peace of mind when sailing out wide another advantage. Give Bud from windsurfing sails a call re: price.
Use 430 rdm 100% naish in my 2013 blades (heavyweight) acceptable in 7m prefer loft bico 460 in it due to the lighter/more responsive tip (bico bottom very similar to firestick 100, top is about half the wall thickness). Feels better in the 6.3 have only sailed that sail in chop though so heavier tip dampens a bit). Done easy 35-37 knots on 7m in chop & flat with both masts so doesn't seem to affect performance too much.