I have an apt-cache for a fairly large and growing number of machines, but I'm having problems...

I'm running the apt-cacher on aUbuntu Gutsy Gibbon box, but it has the following problems...
* Caching and then Delivering Partial downloads to clients.
* Partial downloads / old versions of Release and Package files, mismatched to the Release.gpg files.
* No failover if upstream mirror fails.
* Each client needs has the upstream mirror hardwired into /etc/apt/sources.list, so if upstream mirror fails, I must go to each client and update that.
* Cleanup task sometimes locks up.
* Apt-cacher sometimes locks ups / crashes.

So I'm contemplating trying a different one..
* Is there a more robust apt caching proxy than apt-cacher?
* Should I live in hope that the newer version in Hardy Heron will fix it?
* Should I backport the latest apt-cacher from Debian?

Any suggestions welcome.