Unfortunately those problems are real but I’ve been told that a new release will be out shortly to address a few bugs so perhaps this will help.
If you’d like to try mod_pagespeed make sure you disable compression in WP Super Cache and clear the cache first. Even though the docs state that the module always generates uncompressed HTML it appears to do the opposite. In fact, it tries to load mod_deflate:
# more pagespeed.load
LoadModule pagespeed_module /usr/lib/apache2/modules/mod_pagespeed.so
# Only attempt to load mod_deflate if it hasn’t been loaded already.
LoadModule deflate_module /usr/lib/apache2/modules/mod_deflate.so
I did have problems with dynamic pages. A simple phpinfo() refused to load quite often, and backend requests sometimes became stuck. Load on the server sky rocketed occasionally, usually when the module cache directory was emptied.
For now I’ve turned mod_pagespeed off but that might change as this is a young project and maturing fast! I’ll update this post whenever this happens.