I'm confused then... I had thought that there were API differences (within httpd and apr) between the 2 trees in able to support some of the new features.
I suspect that the biggest pain for a 2.0->2.2 migration (if we keep the delta roughly where we're at now) will be syncing with the deprecated APR functions, but that's more about APR going 1.0 than httpd going to 2.2. -- justin