I run both Chromium (day-to-day) and Firefox (start in private browsing mode, AdBlock, NoScript, Proxy) mainly for this reason. I don't find switching between the two too much of a chore and Firefox has been making gains in the performance stakes for some time. I still prefer Chromium's developer tools over Firebug though.
On another note I've now got to make the choice between Firefox and Chrome on my phone. At the moment I think Firefox is the nicer mobile browser but it's good to have the competition. It also wins points fpr being fully open source.