We've got similar setNAME(pin) functions for hardware serial, I2C, SPI, and they're planned for audio. I'd really like to see FlexCAN use consistent functions.
Also on my todo list is looking into the possibility of a unified CAN base class API. Currently we have similar functionality but different APIs for Teensy, Arduino Due, MCP2551, and ChipKit. My hope is we can make all of the API compatible, so people can share Arduino sketches between them, and also to allow libraries for higher level protocols built on to of CAN to work without being coded to specific hardware.
I agree that we should aim towards consistent APIs, but that would require bigger refactoring of the library so I'll leave it for teachop. In the meantime I've added simplified selection of the alternate pins in the constructor and will push that change to github later today.