@JohnCarter, you put your finger on the dilemma exactly.  Two radically different organizations in esprit. Practice looks the same on the surface but radically different in spirit.  Think of a tumultuous marriage in which the couple stays together for a variety of reasons but the divorce is inevitable and desirable.  From what I gather the main editors of this article consist of a few SGI members, a former but very disillusioned SGI member, and a few scholars of Buddhism who look at the discussion through their own lenses.  I haven't seen a Shoshu editor since I've been active.  I think a Shoshu editor, however, would agree with the bad marriage analogy.  Of course the SGI and NS editors would quarrel who is right, the husband or wife, but would both agree that the divorce is better than the bad marriage.  

 :I have to vehemently disagree with Catflap08 that SGI is an offshoot of the SG.  Makiguchi's journey started with his theory of value creation.  He met a fellow principal who introduced him to a very unique NS priestone who had left the temple to establish an independent office at Tokyo University.  Makiguchi chose to merge the study of the Lotus Sutra with his Value Creation study group rather than join a temple lay group.  There was an associationbut always guarded and uneasy.  As you know, there was a terrible split during the war which resulted in Makiguchi and Toda's jailing. 

 :While in prison Toda had two deep spiritual awakenings that modernized such concepts of Buddha, enlightenment, the Lotus Sutra, and the Bodhisattvas of the Earth.  Ikeda also draws on exttensive readings of Western and Chinese classics.  I am not here to discuss right or wrong theology.  But the SG draws on Value Creation, Nichiren Buddhism, Toda's enlightenment, and Ikeda's studies.   

 :From 1951 to 1991 there was all type of drama: good relations, bad relations, maneuvering on both sides, adaptations.  During these years it was also unclear who was the dog and who was the tail.  It was Toda who revitalized the practice of shakubuku and formatted Gongyo (daily prayers).  Similarities in the practice, yes.  But radically different approaches to inherent understanding of the practice. 

 :Up above Daviler has a very good list of differences.  I'd like to add to them tomorrow.