Prevent features creep by charging double !

Well, this is the very condensed version of Martin Fowler's latest approach to requirement creep. His idea is : (1) 'start by charging the double thus allowing a comfortable buffer for the project' then (2) 'accept all new requirements without charge, in the limits of the buffer', (3) 'explain and agree with the customer that fixed scope approach was a mirage' and (4) live happily ever after.

At first, the approach seemed fine and I especially liked the 'risk mitigation', which is basically: if at step 3 you enter into a conflictual state with the customer and start rejecting/charging features, then at least you had peace of mind during step 2. Without this little stratagem, you'd be anyway into a conflictual state with the customer from the very beginning of the fixed-price project.

What I have some problem accepting is: point 1, charging the double of the usual rate. In his essay, Martin calmly explains since we have better and more productive people, we can actually do the job for less. So, in order to be able to apply this 'recipy', you have to be at least twice more productive than your competition. This basically places you in the upper region of the Gaussian bell, probably somewhere in the top 10% companies. Well, that's a nice audience ! It's always pleasant to know that you have 90% chances of not being able to apply this advice.

The 'double bill' strategy raises another interesting problem. How would you apply this when the customer is internal ? It is known that internal projects are plagued with massive feature creep (and this is probably one of the main reasons why these projects fail so often). By 'charging' your corporate sponsor (generally, upper management) you're either : asking to double the project length or doubling your team size. Both cases, you're in big trouble.

I guess I'll stick to the old way of doing things: providing good visibility on the project status, estimating each new feature request and letting the corporate pitbulls to do the negotiation dance. That is, until I reach that 10% Nirvana where we are allowed to charge the double.