actually larger/longer RDM masts have been around for a while
LOFT and HSM/HotSailsMaui are some examples ...
Have people all switched over to RDM for those sails ? NO
Heavyweights like myself and the middleweight from whom I purchased an HSM SpeedFreak 8.5 all seem to prefer SDM in 460 and up
This does NOT take wave sailing and shore break into consideration
If I was worried more about breakage than feeling/performance perhaps I would also use RDM in the longer lengths
Each to his own I guess ...
Hope it IS what you have been waiting for and all works out