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?