On January 1, 2008 the USGA's ruling allowing manufacturers to create clubs which are adjustable for more than weight (previously the only adjustable element allowable) became effective. As a result, several manufacturers have now developed club fitting systems featuring shafts and club heads that are basically interchangeable with the use of a specially designed hosel and "wrench". This is an exciting offering for consumers wishing to hit different combinations of heads/shafts not only during the fitting process, but also conceivably at the beginning of any stipulated round depending upon conditions. (You will not be permitted to change shafts/heads during a stipulated round). With these systems, it takes only moments to "create" a new club right on the practice tee while you are being fitted.

The potential benefit of having this type of quick interchangeability is that a player can quickly try different combinations of heads and shafts and therefore have virtually instant feedback about launch conditions and ball flight with each specific combination. This could and should make the process more customizable for each player since there could be thousands of combinations.
Some potential downsides to this are that unless each individual shaft and club head have actually been measured, you still don't know just what the particular components' specs are. Regardless of what information is displayed on the shaft or the sole, there is no substitute for actual measurement of each component. Unless the fitting and building process includes a scale, swing weight scale, frequency meter, and shaft pureing device, you may not have accurate data about your particular combination of components.

I believe club fitting is both art and science. The "art" part comes in with the teacher/golf professional who can take into account intangible factors about each person and their golf swing/ball flight/goals/personality/abilities, etc. The "science" of today brings club fitters who can offer launch monitors, load monitors, radar measurements, computer programs with complicated algorithms, etc. It's my opinion that the best fitting scenario involves the player, golf professional, and fitter working in concert.

Without a doubt properly fit clubs are an essential part of playing your best golf. I have not yet personally hit any clubs with the new connection method so I cannot say what they feel like or offer personal experience about their performance. Of course, the manufacturer's claim they perform just like traditionally made clubs (shaft and head connected with epoxy). At this point the technology coming to market in this way is so new I think we can be optimistic about the possibilities and cautious about the process.