*SGI irons tend to clubhead designs featuring a very low Vertical Center of Gravity (VCOG) which helps get the ball up. But, if you have moderate clubhead speed and play an SGI iron with a high-launch shaft, the head + shaft can get the ball up too high for you. This is a problem on windy days.
* (I'm using the Golf Digest categories of SGI, GI and Player's)
When I switched out irons back in 2009, I tried some SGI irons such as Ping G10s and Callaway Big Berthas that had stock high-launch shafts. I later decided on the X20 irons: SGI head with mid-launch Uniflex shafts that delivered a solid medium-height trajectory. Shafts were fine, even on breezy days.
I later switched to X20 Tours to get a smaller head and better feel. The shafts were Project X 5.0 Rifle-Flighted. (Flighting gives a little extra lift on long irons, and prevents ballooning on short irons). These irons have a reputation as extremely easy to hit GI irons.
(My irons are improving; just have a lot of trouble with fairway woods and hybrids).
Check out the recent Golf Digest Hot List issue. It will talk about which irons fit in which category. Note: the categories reflect marketing niches.
If you have time to work on your game, you could probably use GI clubs if you wanted more feel. Remember, get the right shaft for your swing and game - that's half of any club. At a 2012 golf expo, the Ping rep was an area club pro. He said he was fitting 5 to 20 HDCP players with the G20 irons. He was recommending a lot of different shaft models, however, depending on the golfer's game and swing.