Unfortunately, I had to leave San Diego early and miss the Masquerade, and there was a Gatchaman entry this year:
Phil Foglio does a nice introduction:
Here's a longer video of the contestant. The music is Animetal's rendition of the Gatchaman theme.
And here's an earlier contestant from 1998's Comic Con, this time in the OAV version of the costume. The music here is from the American commercial for the OAV.