The i20s you have are great irons. I guess the question is what are you looking to improve from that iron?
If you are chasing more ball speed, then I think it is worth looking for a new iron, but if not, then truly you aren't going to get much more out of switching to another set of non "super engineered" irons.
And to Tyler's point, Ping has definitely pushed back its intended release cycle.
Back to what I was talking about, things like the JPX forged line, P line, Srixon line, Callaway MAVRIK line, Titleist t200 type of irons, with multi material construction, you will see more ball speed out of your irons, so again if that is what you are looking for, I would look at those or if you are a Ping loyalist, the i500.