Re shaft, it’s always hard to generalize what will work for someone else. I play steel in my irons and went with with a graphite steelfiber i95. It’s only about 10 grams lighter than my steel shafts in my irons so not to big an adjustment. If you put a graphite in I would recommend something close to the weight in your current irons (within 10-20 grams lighter.) Personally I couldn’t be happier with shaft and club. If you go with the speedzone, you can buy direct from cobra and an upgraded graphite shaft will only cost you between 15-50 dollars more. The speedzone single irons are on sale for $86 so the whole thing is also going cheaper than a titleist utility iron. I’ve only hit 2 other utility irons but there’s no way I would trade anything for my speedzone. It’s just so easy to hit.