if you use the old file then only a couple of settings are not known which are used in a newer version. You only have to check in config.php which are the new settings which then do not work.
The strange this it that I cannot reproduce your problem.
I switched to the KB display because this is the way windows is doing it an a lot of users are used to this.
About the limits. Most servers have a limit of 2 GB because of a 32 bit apache/php installation.
More interesting are the timeouts on many servers. They have to be high enough. If you have a quite fast lane you should be fine. I have sucessfully tested 1.8 GB. But I have a 10 MB upload at home so it does not took that long