I have a set of KE4 Tour irons- the ones from 2007.  They are still in great shape- I had  been playing other irons but am back to playing them and really like them.  Are there any major differences in newer irons like the KE4 tour + or STi2 that would make upgrading worth it? Unless there are any major advancements or additions etc I would probably stick with these for another year or two.  Thanks.

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