A Progressive Approach to Sales Opportunity Qualification [that isn't BANT]

Like a growing number of other commentators, I have come to believe that the traditional BANT (Budget, Authority, Need and Timeframe) approach to sales opportunity qualification is fundamentally flawed and not fit for purpose when it comes to complex B2B sales.
The fact that over 40% of purchasing projects are ad-hoc rather than formally budgeted is, as I argued in a recent blog, yet another nail in the coffin of this outmoded and discredited methodology. But if not BANT, what can you use instead?
Any alternative approach has to take into account the fundamentally non-linear nature of B2B buying decisions, particularly when they relate to solving a new and unfamiliar problem (as opposed to repeat purchases of well-known commodities).
In such environments, opportunity qualification must be recognised and managed as a progressive rather than a one-off process – often starting with marketing, involving some form of tele-qualification and with responsibility passing