Dear Steve, I used to do research on internet protocols, and understand well the best-effort nature of the IP network. Your explanation makes perfect sense.
My previous understanding was that, under the old system, Obi's were not officially supported, and thus Obi used some hacks to appear to be a Google Talk browser session to the Google servers. Now, as I understand it, Obi is officially supported by GV, although it is unclear whether Obi made any changes (less-hacky) after this happened. I guess my refined question is this: "Since Google now officially sanctions Obi's (they even have the logo!), is there any noticeable improvement in call quality and reliability?" I ask because, in the olden days, I had only so-so quality with GV over Obi.