Some interesting quadrangulate reading.

 From:  Michael Gibson
2772.2 In reply to 2772.1 
Hi PaQ, just a note - often times the research into those areas are oriented towards producing regular meshes for Finite Element Analysis processing (like for structural strength analysis) rather than for use as sub-d cages. Sub-d can be more sensitive to some things such as areas with poles...

So I don't think that a general quadrangulation mechanism is necessarily the same thing as a "make perfect sub-d control cage" mechanism....

- Michael