generic IP proxy

I have an office where we have two broadband connections from two differnet
providers - each with a static IP. I am using a Xincom twin WAN router to
*shotgun* these connections, so there is automatic failover if one of the
connections goes down. This works great for internal traffic wanting to get
out.

I think hosting email at this office will immediately benefit from the two
connections because I can add each of the two outside IPs as an MX record or
different priority...please let me know if I am missing something in this
assumption...

Now, for hosting other apps (web, XML-RPC server), would a *generic* proxy
(http://www.quietsche-entchen.de/software/tcpproxy.html) work? By hosting
the generic proxy at a site with much higher uptimes, I could route through
to either of the two broadband connections, depending on which one is up...

any advice appreciated.