Looking at my styles, I do the same thing you did, actually typed PVC and PVT within the text component. Couldn't find an option that would use the abbreviations from the drawing settings. Looked at the out of the box template for profile labels they did the same as us, but within the alignment labels, they were able to choose Geometry Point Text, which uses the abbreviations for the point type. Not sure why it is not included in profile labels, with that text component, label would always change based on the actual point type.
Steve Goessling
Land Consultants
Civil3D 2015
Windows 7, 64 bit
Intel i7 2600 @ 3.40Ghz
16 GB RAM
Nvidia Quadro 600