I'm not running apache 2.x in production, but that's because we've been using apache 1.3 for about 4 years now and it works just fine for us.
The reason they recommend not using 2.0 in production is because while Apache 2.0 and PHP 4.x are both fully thread safe, some of the libs that PHP connects into aren't, and if you run apache/PHP in a multi-threaded mode you can get unexpected results (i.e. apache backends may start crashing, and since they're threaded, many backends crash at once! yaay!)
So, as long as you configure apache 2.0 to run in multi-process mode, it should be stable.