Some say dynamic spine is the way to sort arrows, some like the static spine to fletch arrows with the high or low spine is the same spot. Personnaly, I like the extra piece of mind of fletching with the high spine is a certain spot. I have not had any problems doing this and I have not had to rotate any nocks to get the arrows to group.
If you start testing shafts, you will be amazed at the differences in spine of one shaft versus another shaft and within the same shaft itself (high to low). You will also begin to see which shafts are the most consistant and don't even need to be checked.
So, IMO, if you have the money to spend on this device, then I think it would be worth it. I had access to all the tools and materials to build my own spine tester to do what I wanted it to do, and it has been worth it.
Just be prepared to let your friends either borrow it or bring their shafts over to your house for testing (unless you keep it a secret).