It may seem as though the putter shaft could have little to no difference but then I gave it a try...
I was not convinced that a shaft at such low speed and under no real load could have a drastic impact.
Although I have built and fit custom putters for almost a decade, have a good understanding on how a putter fitting/ putter build can help a players stroke and know what needs to occur at impact to give consistent roll and feel. I have never really explored shafts in this much depth.
The concept of the putter shaft making a difference has been around as long as I have been fitting but it has always seemed to have limitations (styles of putters that specialised shafts can be used in has been a big issue) and lack of evidence to back up the claims of performance enhancement.
Finally I think the industry is ready for this product.
We now have accurate measures on ball speed, heel/toe deflection, face angle control, strike consistency, ball roll efficiency and much more.
Although it is hard to demonstrate during a fitting that the Stability shaft has an immediate effect (without dismantling a players existing putter or your fitting stock) I am certain most players can benefit (if fit properly will all other components).
The stiffer flex and lower torque concept is more stable and the evidence of control pre and post impact is clear when measured.
Don't get me wrong a lot of components need to come together for the shaft to make a significant impact on your scores but once you get them all correct there will be no going back.
You need to be able to aim your putter well, have the correct style head, weight and balance putter. Loft and lie need to be correct, the correct grip needs to be installed and you need to be making a nice move at the ball to see and feel results properly.
With a good session from a fitter / coach this can all be achieved.
One issue that can occur is that swing weight increases with the installation of the stability shaft. For most players I see positive results from them getting a feeling of more head weight but in some cases this can cause issues with tempo and path. Again, if fit properly this will be taken into account, but this is definitely something to look out for.
I haven't really touched on the look and feel of the stability shaft but take it from me that the feel is something I have never felt before (in a good way) and the look .... pictures say a thousand words!
One final aside is that after experiencing the results with the change of putter shaft (the club under the least speed pressure in the bag) and seeing results myself is it enforces my work with players on every other shaft in the bag. When your clubs are fit and built well for you, you will have better control of the ball. From the putter under almost no pressure to wedges under soft pressure and the all out speed of a driver swing, you need the shaft to work with you. As speed increases stability of shaft becomes more and more paramount.
Think about where you want accuracy and control in your bag and go searching for the best results you can get.
THIS MAY READ AS THOUGH I WORK FOR STABILITY. I DO NOT, I JUST WANT PEOPLE TO "PLAY BETTER GOLF".