if i recall correctly, now iccf only allows members to download their games or something, not sure. another centaur server is ficgs. [edit after seeing post below: ok nvm, that's cool]
i guess you can try asking an expert: http://www.chess.com/blog/FirebrandX/winning-the-19th-usa-cc-championship
Recently on one of these threads, someone said that a Centaur (human+computer) playing on correspondence time controls (24h+ per move) are stronger than computers alone (which means their rating must be something above 3400 at least).
In that case, I would be highly interested in seeing those games, so the question is: Where are those games/tournaments available in the internet?
Thx