I too am a new user (from Vonage) and chose to hold off on porting until I am satisfied with the service. Vonage lets me forward the number so incoming calls work fine, and outgoing calls show my "real" number by default.

They sent me an RTP312 and MOSTLY it has worked fine, except that within a day after I received it it stopped communicating with the Internet and I had to power-cycle it. This has not recurred so far (couple of days now.)

The calls I have made and received have been fine, but I have not tested extensively yet.