If you have installed a personal copy of Zimbra, another thing you can do is use the zmmailbox command to reload your feeds:
You could create a file with sync commands in it:
/opt/zimbra/bin/zmmailbox -z -m user1 syncfolder /feeds/digg
And then run zmmailbox out of cron with the -f option and point at the file.
We definitely need to put some more work into RSS though, what we have today is very minimal.
I'd suggest filing a bug on being able to specify a default view for a folder, as well as an option to sync all RSS feed folders.
I also though we had fixed all bugs related to authenticated feeds, but I could be wrong.