Anders, 

The Spin Milled (SM2) were the generation of Vokeys that were introduced roughly a year before the groove rule change.  Once players needed a conforming wedge, we came out with the SM C-C.  This wedge has legal grooves offering less spin and a slightly higher launch.  The SM4 was released this year and offers a few differences then both.  The head design has more of a tear drop look to it.  Also, the grooves have are bigger and offer more spin then the C-C wedges.  This is because we have pushed the limits to the max on how deep and sharp these grooves can be (while staying within the boundaries of the Rules of Golf).  We have also head treated the faces on the SM4 wedges, allowing for the grooves to be more durable and longer lasting.  

To learn more about all of these wedges, click on this link:

http://www.titleist.com/golf-clubs/wedges/default.aspx

Cameron

1-888-TITLEIST 

Continuing on.....  The 50-08 has been a go to club for close to a year now and the recent modification I made to it makes more deadly on the bump and run shots.   I had a choice of buying the SM4 54-14 or the SM c-c 54-14 and went with the latter mainly because of the narrower sole; the latter works equally well off tight lies as in soft sand or thick grass.

I'm slowly finding out I can use the 54-14 in wet sand - key is to only slightly open the clubface.  I applied some tips from the Golf Fix on wet and hard bunkers.

I like all 3.

Played an SM2 60-07 and 64-07 between mid 2009 thru mid 2011. 

When I upgraded my irons I bought a Spin Milled c-c 54-11 (bent to 55).  That is a rather versatile club. 

I have been playing  a Spin Milled c-c 50-08 since summer 2011 and that made less work of my 30-80 yard approach shots.  When I played with my Eye 2s, I left it at stock length with the loft 51.  When I switched to AP1s, I shortened it to 35.25" and set the loft at 49 (also now works better on long bunker shots).  I do a lot of my pitching with this club.

I played with a Spin Milled c-c 62-07 between June of last year and May of this year.  The main reason I got it was it did the same as both the 60-07 and 64-07 together.

Briefly used a SM cc 58-04 between October of last year  and this May - main purpose was to fill the gap between the 62-07 and the 54.

Recently got an SM4 60-10 (bent to 59) and it has been a go to club in greenside bunkers and around the greens.  It stops the ball better than the 62-07 and simplifies the wedge setup.

Traded the 54-11 for 54-14 (bent to 53).  The 54-14 has been working better around the greens and is available for very soft bunkers.