It's a nice idea, but I'd like to see some examples of this in practice. One problem I see with this particular system is one of relative scale, in that your x,y,z and a,b,c and p,q,r triples all need to be somewhat-carefully tuned to remain on the same numerical order of magnitude. I wonder if a better system can be constructed that depends more on the relative rankings within each category, and less on absolute quantities.<p>That said, I've started using another system that a coworker recently introduced me to. He likes to model the total business value of an improvement or cost-savings as a discounted cash flow. You estimate the gain as a cash flow per period, and run that through the standard present-value formulas, either picking a discount rate out of a hat or using a range of discount rates to see how the results vary. You can then compare this to your total estimated cost (e.g. your hourly rate times the expected hours of work) to see if the thing is worth doing.