Well, it was some time since I sailed an SDM, but the foling _can_ happen with these mast too. Some SDMs are actually quite soft (NEVER trust a printed IMCS number). That said, the "typical" rdm acts a bit softer than the "typical" sdm down the middle of the mast, I would say. IN the case of RDM, the Powerex is pretty much the standards mast and is a bit soft in its mid part in 400 length (and even softer in 430). The GT needle 100 400 holds up a bit better to long extensioning, I would say and the reason is that it stiffer i the mid part. The Hot Rod is stiffer still but both still fall within the "PX norm" is fit sails cut for Powerex well.