I recently changed from Mozilla to Firebird (browser) and Thunderbird (mailnews).
I used to not like Firebird, but now I've managed to find out enough about it to customise it to be as close as possible to Mozilla the browser, and avoiding the IE-a-likeness about it. Thunderbird is good enough to replace Mozilla Mail, IMO, and my requirements for a mail client are many :-) I thought I'd explain that as people might be pointing fingers at me, as I have been a strong Mozilla (and not Firebird) supporter in the past.
Anyway, back on point. Firebird/Thunderbird /might be a more practical option for AmigaOS, if there is a GUI toolkit capable of providing everything they need. I'm not sure there is. Admittedly some of the features, like the way toolbar customisation is implemented, could be reworked, so that it isn't a 100% accurate port, but hmm.