There is special approval required for IAN? Wasn't aware of that, and as far as i know IAN is standard equipment from a certain MSN on.
Unfortunately no, still optional...
I'd say if you have dual GPS, good ANP and coded approach, LNAV/VNAV (or IAN if you're lucky) is the way to go. Makes it much easier and you can still monitor the needles/DME on ND.