I would like to use Waterfox for everything as it is currently the browser that is close to good.
But Google is so bad at programming that their code only works well with chrome so I use chrome for Gmail, Google maps and so on. So I have a chrome window up with 3-4 tabs normally. But as chrome takes so much memory extra for each tab it cannot be used for more uses.
Too many products like old firewalls boxes, Microsoft remote connector and similar require IE. Thus I find myself running it almost every week for something.
And finally Firefox is really really bad with bad certificates. I have to often do things like manage networking gear that has expired certificates and similar. Firefox just says "you cannot do that" where with Chrome I can say "yes I know it is insecure, but I really do not care" Thus I have to use chrome almost weekly for such.
But for the rest of it.. yes Waterfox is the way to go. Currently 5 open windows with 150+ total tabs in waterfox.
When Mozilla gets their Windows 64 bit Firefox version running and stable I will likely switch to it.