From Alado's website: http://www.aladous.com/sheaves.htm]
Since there are no hanks, high halyard tension is not required and no halyard loads are applied to the mast.
Make's me wonder how much they sail themselves? It is highly desirable to be able to change luff tension to match conditions.
As for applying halyard loads to the mast - That's one of the things it's build for
That alone would make me look for another furler, and if the Harken unit is cheaper, it's a no-brainer isn't it