Which six sigma concept do you implement?

Your professional focus and previous questions indicate to me your business is in trying to work out where and how to get "lean". Not that all operations shouldn't pursue this end but mid-sized manufacturers are in that odd position of having certain economic constraints and enough differentiated management to question "how do we change" at a department/function level.

The scope and requirements of Six Sigma as a "management system" are beyond most organizations. The likes of GE and Motorola have enough excess managerial capacity and money to institutionalize change at that level. In GE's case this was done when Jack Welch lead with extreme powers - a useful state. In my oppinion, considering the level of understanding and time/money available, smaller organizations might better encourage learning Bodies of Knowledge such as CPIM or CSCP promoted by APICS.

The Six Sigma "measure" bit may be something of a misnomer. Most programs drive for savings based in improved quality (product and process.) Sometimes those quality changes are evaluated as continuing improvements i.e. stable reductions in waste. You don't necessarily need the level of statistics implied in the discipline. Measurement is important for lots of reasons but it shouldn't be an end in itself.

I believe good payback for SMBs comes from "lean" efforts, which includes the use of a wide range of tools including the DMAIC project management method. The statistical quality control tools can be very valuable in manufacturing and other operations. No less important is the clarity and throughput to be gained in back-office operations by analyzing value streams and eliminating non-value added procedures.