My 2p worth seeing as I'm just about to order a MP18 combo set.
I got fitted 2 days ago, had my heart set on the JPX919 Tours, no doubt they are great clubs and I was impressed (currently gaming MP5's), but for me, the MP's have the edge.
I hit the SC's and was amazed, these are the real deal.
I am going 4-8 in the SC's and 9 and PW in the 18 blade.
The SC's are not difficult to hit in my opinion. Was hitting the 6 iron and finding the middle of the club more often than not but even slight mishits were fine. Not a huge amount of yardage drop off.
Hope that helps,
Ian
PS Basically JPX or MP's you can't go wrong - I have hit dozens of irons and always always come back to Mizuno, the only thing close is Srixon.