Appreciate the question, I like to approach policy concerns such as this in a more socially holistic way - basically the question is will society make correct/intelligent decisions? For your question it is in regards to budgeting, but a similar fear or argument could be applied to any area of governance.
You mention natural bias/impulse voting, I am going to lump them into the grouping of unintelligent decisions, ie the population is making a decision based on selfish wants without the thought of the longer term damage such policy will result in.
My personal view is Flux or any DD political movement should not implement any measures to avoid such decisions. Why, because who is to say what is intelligent and what is not, as soon as you do you are creating an oppressive authoritarian system. The makers of Flux, or yourself, or me, may have clear ideas on what are bad decisions, but are we correct? Do we even agree? Why are our opinions more valuable than any other persons? Under DD we are all equal.
Whatever mistakes the population makes under a DD system, they are responsible for them, and they live with the consequences. Personally I think DD will be a mess. At the start. The average person has little understanding of effective budgeting, international trade, finances, immigration policy, anything.
Under the current system why would anyone educate themselves on policy? You don't get to vote on policy, your representatives often obscure their stances on policy, and you are forced to choose some omnibus representative/party and take all their policies or none of them. Its a messy system that melts your brain every election cycle if you try to work out what demagogue is going to deliver what. Better to relax and watch T.V.
Then you bring in DD, and policy level discussion and education suddenly means something, there is direct value in educating yourself and educating your children to create better policy.