Zafira,
The Adams a4OS irons are one of the more forgiving Hybrid irons is golf.
I don't personally play the a4OS but I am very familiar with their performance benefits. The set is designed to give you maximum forgiveness in each individual club. The 3-5 hybrids are great for getting the ball out of some of the tougher lies you will come across (divots/deep grass). Also, if you struggle with your trajectory, the hybrids will get your shots up off the fairway quicker and will carrying farther than more traditional long irons. What sets the a4OS apart from other hybrid irons is the forgiveness of the mid-short irons. As you can see in the picture below, the set transitions from a Hybrid to a almost hybrid like iron
(click on the image below to view a hi-resolution image of the complete set)

The 6-pw, having a tungsten notch weighting design on the sole/back cavity, will vibrate less on mishits & give you more of a mid trajectory. As for the choice between
Steel or Graphite, I would choose the graphite model. The steel set has the steel shafts in the 6-pw, while the hybrids are still graphite. Unless you have a strong/fast clubhead speed, the graphite shafted set is more forgiving.
Overall If you are a mid to high handicapper, the a4OS would be a great set!