Unfortunate event, but leads to a great opportunity to get gap fitted from your 9I to your SW.  My former PW was a 44 degree and my current AP1 is 45 and my GW is a 48.  I thought about skipping the PW, but my fitter encouraged me to add one for resale purposes.  Every 3 or 4 rounds I get the perfect distance with a soft green and a rear pin where the 48 is too short on a full swing,  Otherwise I prefer the feel of the forged Vokey.  You and your fitter should be able to fill in your set with Vokeys.

I have an AP1 PW.   My GW is a 50-08 bent to 51 and SW is 54-11 bent to 55.   Only have a 15 yard gap between the AP1 and the 50-08 but choke down on the AP1 to fill the gap.

If your a non tournament golfer and all your wedges are non conforming to the new rules, i would just get a PW in the old spin milled, but if your other wedges are conforming go ahead and get the SM4. I currently have a 54 and 58 in the SM4 and i love it. But going on with the PW, in my old set i had a 48 degree Vokey Spin Milled and it was awesome, it was much more versatile compared to a normal PW, i was able to hit delicate chips with it from deep rough becasue of the sharper leading edge.

I was thinking about that but all my wedges ( 52, 56, 60) are CC so I thought I would go with the Sm4 to get similar spin.  I have it now and LOVE it!  Hitting my 3 wood on some par 4's just so I can use it .  

I started using a 48-06 SM4 as my PW after using the "stock" PW from my iron sets for years - it's been a great move for me. I have  a lot more confidence in the club (based on other Vokey wedges), my distance improved 10+ yds (even with the slightly higher loft) and I get more spin. In fact I just ordered a custom 248-06 so I definitely think it's a good move

I have a 56* and I love it. Great ball control on the green. 

I switched to a Vokey SM4 46.08 pitching wedge from my stock 710 MB pitching wedge.  I liked the switch because of the weight distribution on the Vokey compared to the stock 710 MB.  If and when I hit the Vokey solidly, the impact is better because the muscle is located lower, thus creating more force directed towards the ball.

I would note, that it is easy to mishit and not get enough force onto the ball if you hit it on the high end of the face because the weight is lower.  I would recommend switching based on course condition, as I do.

When I got fitted for new irons and wedges last month I decided to go SM4. I am using a 48* (bent to 47*). They're great, more feel when hitting shots.  They even have larger sweet spot than a regular PW.  Better performance around the green, gives more spin.

Just make sure you fill-in your gaps correctly.  Good luck.

Carlo

Didn't buy an actual PW, but bought a sm4 50 this year and it has performed great.  It filled the ugly gap I had from 110-120.  My old i15 GW was very inconsistent in regards to yardage, which from that distance can be a killer.  My new 50 sm4 goes the exact same yardage, swing after swing.  I feel like I can manipulate the flight better too depending on wind and when hitting over obstacles.  I love it.  I dont mean to badmouth Ping, and still like the rest of my i15s, but have 3 vokeys in the bag (50,54,58) as my scoring clubs.  My advice would be to demo one on the range, or even better, on the course if your club allows so you can see how the ball reacts when it hits a green.  I think you will be very happy.  At least here, Titleist reps will bring vokeys along to the demo days.

I had Eye 2 irons before getting my AP1s.  Didn't use the Eye 2 PW or SW (used Vokeys 50-08, 54-11) because they were absolutely horrible around the greens (OK out of bunkers and soft lies).  The Eye 2 irons were good at sticking the greens (I gained a club using AP1s due to 1 club stronger loft).