Brian,
That appears to me to be a very big "if" except for large and sophisticated customers; it seems to me that the large majority of medium size sites will be very unlikely to run an ETR, even if they are connected to more than one ISP.
I think this depends on the complexity of running one. If it adds no operational complexity, why not have them in a Linksys box?
Eliot -- to unsubscribe send a message to rrg-request@psg.com with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg