I’ve got a set of irons for both, a golf buddy has a friend learning and tried both sets wanted to know which set would be better long term. The 6DX has a tungsten insert and from my search online I couldn’t find much info besides ultra game improvement which includes the gi 7DX, I took a set of UST graphite shafts out of some 3DX irons as the infill has deteriorated badly and I don’t know if that can be replaced. The UST shafts fit the 6dx and 7dx heads so thinking they may be better than the steel, I did see the Golfworks listing on Nickent clubs but it only shows upto 5DX so hoping you can add some insight. It looks like the 6dx tungsten irons were first sold in 2010 at least that’s what I read online, appreciate your feedback. Cheers Colin..