I lab tested the MB UL Down Inner at 1.78 Iclo. The Pat Nano Puff wasn't tested. You are correct that the specs for Nano Puff should give it a 1.51 Iclo; so, theoretically the jackets should provide equivalent warmth.
Unfortunately all of the synthetic jackets I tested, from many different manufacturers, using many different types of synthetic insulations, tested significantly lower than their insulation specs. The closest synthetic insulation jacket to the Nano Puff, that I tested, was the MB Thermawrap jacket (50g/m2 Exceloft). It lab tested .48 Iclo versus its theoretical 1.26 Iclo.