After looking over their options, I believe that they might try to bump me up to a dedicated server and charge me $100 a month. My service has been pretty good for at least the last 6 months for a lot less money. I see no reason to switch, since we currently use about half the bandwidth that is allocated to me.
There are all kinds of ways that hosting companies can limit your use. They can shut off your site at their perogative if they think you are using too many resources (not just bandwidth). As long as f5hosting doesn't start doing that again, I see no reason to switch.