I have to say that this is the first time I have heard anyone complaining that a Suunto was more liberal! That seems to be your biggest concern so I checked. Admittedly I am running it through a Cressi not a Suunto but they both use modified versions of the RGBM so I think the comparisons are valid for a first dive NDL...
On first dives with both set for nitrox 32, the Cressi and the Petrel set at most liberal (rec mode), the Petrel gives consistently longer NDL's until about 90, then the Cressi NDL starts to exceed the Petrel. So unless your dives are greater then 90 feet, set your Perdix to low and no worries. Even at 100 the difference is only 3 minutes.
With the Cressi still set "liberal" and the Petrel on medium, the difference starts at around 60 feet. With the Petrl on High, the margin is fairly wide even at 60.