Any raim warning when using the GPS below the MSA in IMC requires you to fly the published missed approach.
This applies to a VOR/NDB DME approach which has a lower minima due to the increased accuracy from he DME/GPS.
This also applies to a GPS/DME arrival as you're using the GPS for the steps.
It certainly applies for a GPS RNAV.
If RAIM isn't available, do another type of approach!