The main issue scaling traffic has been the range request handling in Squid/Lusca, so I've been working on fixing things up "just enough" to make it work in the firefox update environment. I think I've finally figured it out - and figured out the bugs in the range request handling in Squid too! - so I'll push out some updates to the network next week and throw it some more traffic.
I really am hoping to ramp traffic up past the gigabit mark once this is done. We'll just have to see!