If the motivation to go to a shorter driver is to gain more control and consistency, that’s understandable. Shorter drivers are easier to hit solid more often than longer length drivers. I have to assume you are going to a softer flex because your clubhead speed has dropped some and you no longer need the S flex. I always hesitate to recommend heavier shafts when there are so many really great options in below 70 gram shafts that can help those that struggle with generating clubhead speed with their driver. You can loose some overall weight feel when going to a shorter driver and for that reason if you wanted to maintain some of the “heft” you felt with the longer driver, then using a heavier shaft might help with that. However, everything we change in our golf equipment has a trade off. If you go to a heavier shaft, you will increase the overall weight and that can negatively effect distance. If you could stay with a lighter shaft and increase the head weight slightly, you could maintain the clubhead feel you had at the longer length without going to a heavier shaft. I know you would still be increasing the overall weight of the club either way, but by adding the weight back to the head, the balance point stays lower and I believe the loss of clubhead speed from the shorter club is not as significant. It really comes down the combination that gives you the best feel and performance, and only you can know if the heavier, weaker shaft at the shorter length will provide that combination, or if a lighter, more flexible shaft at a shorter length with added head weight would be better. May take some experimentation.