I put one in my custom Vokey wedge, it gave me a little more feel, it's in my sixty degree so have not noticed any yardage gain, but it does feel great.

I have heard over time they start to crack and wear down. But that was only a couple experiences, I would look at the pros and cons, and then give them a shot!

Steel Fiber is something I have never known about. Never knew it existed.

I have played SteelFiber shafts for about the last 4 years. The distance gain was very minimal but the feel difference and the shock threw the club was the big difference.I also have not seen any cracking or problems with the shafts.

I picked up a 3 iron with a steel fiber 125x shaft in it, I really like it for the few times i have used it so far. I dont think i gained any distance with it, but the ball flight seems a little higher then a steel shafted 3 iron.

I've been playing them for the last three years. They fight the shock like graphite, but give you the feel and playability of steel. I have the i95's in my irons and the i110's in my wedges. I'll never play any other shaft again, they are that good - for my game.

I went from S300's in my AP2 714's to Steelfiber i95 stiff. Distances are within a few yards on Trackman and spin was very similar. For me it was my wrists and elbows that were getting hammered. Noticeable difference with the Steelfibers!
As to durability I have literally never heard anything like that - if anything I'd think they were just as durable as steel since they are wrapped in literally miles of steel wire.
The flex pattern and feel is different than a plain-Jane steel shaft so make sure you do a blind test with BOTH flexes before you commit.

I tried steel fiber in my 714 AP2's over the DG steel 2 yrs ago, felt good than that of the steel. But this year I went and got fitted with UST Recoil F3 carbon Fiber shafts. I gave them a 90 day trial and I now wish I had gone to these sooner. Now they are in both my sets, the 714 AP2 and 714 MB also my SM5 wedges.