I’m somewhat in the same boat. 110 driver swing speed but have played stiff shafts my entire life. I demo’d some of the 2024 drivers and the pro suggest x stiff. I found that I had less shot shape and a miss was either a push, straight, or pull. Yardages were up though. I think I’m going x stiff when I decide to replace my broken TSR.

Y’all know there is no standard for flex. It is only applicable between the same shaft with 2 flexes. One company’s stiff maybe stiffer than another company’s x-stiff. Speed is only one factor. Transition is another.

When I go for a fitting, I don’t look at the shaft for which shaft it is, let alone flex. We keep it a secret until the fitter says we’ve optimized the shaft. My only input is to comment if it feels too stiff, loose, or just right.

If you liked the feel and the performance of the shaft selected, go with it. It doesn’t make you an X-Stiff user all the time. Just for that model.

Like your approach to shaft selection. My current irons are T-200 AMT 2 Red senior flex. My fitter handed me a T-150 and said hit it, w/o asking the particulars of the shaft I proceeded to hit a few shots. Improvements in the numbers all around and guess what, the shaft was a regular 95 gram Aerotech steelfiber . Go figure

Same boat for me. I went with the stiff option as opposed to X, simply because I'm middle aged, not getting any younger, and was concerned about losing some clubhead speed with the X flex (not sure if this would actually happen or if it's in my head). Can confirm that the X stiff felt slightly more stable, so the dispersion should be tighter. At least that's how I see it.

I have always played Stiff flex and currently have driver swing speed of 110 mph (was 115 mph in my prime). I always thought X stiff was for elite players. I think that was the case back when there were fewer shaft options. But now I think shafts are so good and there are more options so X stiff can work for recreational golfers or slower swing speeds. I had trouble finding a 3 wood I could hit off the deck, always played S flex. Got fit last year with Titieliest fitter and wound up with the Project X Hzrds 4G 6.5 flex in a TSR3. I think the 6.5 might be in between S and X stiff. It feels a lot firmer than my previous S flex 3 wood and is a lot easier to hit with less dispersion. I am upgrading the driver this month and the irons later in the year,. I expect I will be in the Project X 6.5 in the driver as well.

I wouldn’t be afraid to go X stiff if you got the ball flight you wanted in the fitting. It’s not just about swing speed anymore. I know a guy with 90 mph driver swing speed that was fit X stiff. I think it was the lightest X stiff shaft in whatever brand shaft it was.

As a fitter I would recommend sticking with whatever the fitter determined was best. As Don said there is no standard for shaft flexes. I have said for a long time manufacturers should eliminate 'flex' from the vocabulary and do something similar to Project X and have a number designation. Players too often get caught up in the flex and don't realize the other properties and effects different shafts have regardless of what flex is on the shaft.

If you trusted your fitter and feel like you got a proper fitting I would listen to the professional.

As a Titleist Performance Institute medical provider, I would encourage you to consider if you are participating in the gym and exercises to improve your strength and swing speed or if you are just interested in playing golf and maintaining the status quo as you age.
If you are active in the gym and looking to approve your strength and speed, then it would make sense to go with the more stiff shaft for your clubs. I am 50 years old and that’s what I have done and the shafts work out great for me.
Keep up the good work and keep those shots on target! .