CDN images + Absolute Filesystem Path + Private files

I have a relatively complex setup:

* Imagecache module
* CDN module
* Boost
* Pressflow
* Ubercart

I have a load balanced setup as follows:

1) Files are all places on a shared NFS mount.
2) Files are sync'd to each webservers local drive at a regular interval.

This has created some performance problems and subsequently the vhost can not be configured to serve from the NFS mount.

So I've switched the Drupal/Pressflow FS path to point to the NFS mount (so uploaded files are written to one place and sync'd out). I've also switched the FS to serve files privately (through drupal. Although public would be much nicer).

The issue this has created is all CDN'd images (displayed via ubercart 'category' pages) are linking like this: http://domain.com/absolute/file/system/path/causing/404s

To be fair, I'm not sure if this is an issue with CDN as theres a lot of modules at play, but this seems like an incredibly specific use case that shouldn't be too out of the norm.