Magnepan 1.7i compared to older 1.7

Anyone upgraded from 1.7 to 1.7i?  I read somewhere that the new "i" is smoother. I've always felt my 1.7s were plenty smooth and wouldn't want any reduction in upper detail. Many cross over part improvement/upgrades can smooth things out with out rolling off the top.  I specifically want to know if the new 1.7i  is just as extended at the top as the 1.7? 
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I had both but at different times so no A/B comparison. The reason I changed was the i was a great price in a location I could pick up.
I would say a good sub makes much more of an improvement in sound.