I don't speak when I don't know what I'm talking about (or generally I try to follow this). When I'm debating, it's something I know well and usually feel strongly about. I don't argue with everyone I see for the sake of arguing, but I love to ponder about all the different aspects and perspectives of issues I care about.
Your Ti Ne process describes me better than the Ne Ti process does. However, it's not unusual for even a strong introvert to show a bit of extroversion around people they're comfortable expressing themselves to. I have fun arguing against my family members/myself, but generally I like to have all the logical arguments planned out beforehand.