Does find my iPhone still work if I transfer my number to another device?
If you transfer the number to a new cellular data plan, and the phone is not connected to a wifi hotspot, your phone won't be able to report current GPS coordinates to Apple's Find My Phone servers. In short, I think the answer is no, but as @HLLB pointed out, your phone's battery will probably die before the phone number port is completed, so better get to digging!