John,
Any likely problems with setting ProxyTimeOut to 120?
Or is that a Directive whose value is commonly increased?
In my opinion, proxy timeout or any other time out limits should be little bit higher than the longest running transaction in your application. For example, if you see some file import takes three minutes to complete under loaded system and if that is your longest running transaction, I will suggest to set all timeout limits to accommodate that process.
If you set this value too high, thread pool exhaustion can happen if you have a very slow performing backend server.
