When the double tilt upgrade came out, I wanted one. But I've come to the conclusion I will probably never own a Power Pro headstock. And I can't think of a good reason to get the double tilt if I don't have the Power Pro. Someone convince me otherwise.
That will be very hard (if not impossible) for me to do. I have no PowerPro and will almost certainly never have one BUT I have the Double Tilt Upgrade.
For me getting it was for a different purpose. I believed that without it I would never be able to maintain total alignment to the level of accuracy that I wanted.
With that purpose in mind, I consider my purchase of the upgrade a total success. If you are satisfied with your alignments the upgrade would be an unwise investment. I am pleased with mine.