The welding on duplex that has been using NiCrMo-3 for the filler metal. The roots were welded with GTAW and the remainder with GMAW-P. These welds were shop welds but made in position.
The pipe welds were only VT'd and PT'd and came out ok. The remainder of the product was 5/8" 2205 shell sections . All welds were flat, vertical or horizontal. The GMAW-P process was specified by the end user and we didn't hasve anything to compare it too BUT the process is prone to non fusion defects in my opinion if the parameters are not controlled.
Excess puddle size and to narrow of a groove was a killer.
If you are able to roll out the welds, I would think GMAW Spray would be better. Duplex has some issues with time at certain temps but I don't thing that would be a concern.
My experience with the material is only for a couple of years involved with scrubber fabrication so I think some more detailed advice may come.