Hey Donncha, thanks for the plugin as always and for being so active on the forums supporting it (the number of supercache threads is almost as scary as the number where you replied is impressive).
As I imagine you are aware, WP-Super-Cache is not WP_DEBUG compatible and running them together results in a lot of log cruft like
Undefined index: HTTP_X_FORWARDED_PROTO and
Undefined index: HTTPS and
Constant WPCACHEHOME already defined.
I think if you enabled WP_DEBUG and kept an eye on the logs you could clean up a LOT of the issues without creating any bugs or using up too much time, and it would make it way more pleasant to debug staging sites where keeping Supercache active is relevant to making sure things will work properly on live.
Thanks for considering it.