Back to Nginx
After much head scratching, I just realized after re-reading the specs of mod_proxy in 1.3 spec that the mod_proxy version for apache 1.3.x doesn’t support the style
ProxyPass /images !
Looking closely at the spec
Syntax: ProxyPass path url
Default: None
vs this one (in the 2.0 spec)
Description: Maps remote servers into the local server URL-space
Syntax: ProxyPass [path] !|url
pretty much shows the unobvious difference that there is an exclamation point for v2.0 onwards.
With all that, I have opted to return to nginx (at least for now) with the new setup. Right now everything seems blazingly fast (and nginx has a new release, surprise surprise) so at long last, mongrel is no longer serving static files..