I emphatically disagree with the proposition that ACT should once again try to tie their factions together. It shouldn't aim to be the "broad church" that is the National Party. It should declare itself economically and socially conservative. How hard is that?
Then those people who are ecomically conservative and socially liberal know where they stand and can act accordingly.
It still remains for those who reject ACT (or whatever Banks decides to call it) to form a new entity that does manage the differences that will inevitably arise because people are always somewhere along a spectrum. But there needn't be differences as gaping as those between people at opposite ends of the social spectrum.
It'll take goodwill, genuine compromise and committment to discipline. But I ask you, what else is left?