First, kudos to DiscreetFX for AmiZilla site and the Firefox port initiative.
This forum often has too many naysayers - for a forum which is dedicated to Amiga enthusiasts I find that a bit strange sometimes.
Yes, porting a modern browser seems like an impossible task but that's what makes it so appealing

. Compromises will have to be made.
I agree that running Firefox on a machine with less than 8MB of ram is not viable. Even if it was possible, memory available after launching the browser would be minimal.
You can think of a single Firefox tab as a 1MB "footprint" in memory. This means that a fully featured firefox could not drive (realistically) more than 1-3 tabs on an Amiga (with 8MB ram). As an experiment, I am writing a plugin (for a PC) which will eliminate the need for multiple tabs (which consume extra memory). The basic idea is that a tab can be represented in two ways: as a memory buffer or as a file (in the file system). Memory buffer won't work on an Amiga because of memory constraints. "File buffer" would work nicely (with a hard drive, of course). This measure alone reduces the need for RAM. I often have a large number of tabs open and think that memory footprint of Firefox is pretty big under heavy use. It does not have to be because I am working with 1-2 tabs at most and the rest are just consuming ram

It is difficult to estimate how big or small the core of ported Firefox would be. Amiga's binaries tend to be very compact but that alone cannot guarantee a small footprint. Once again, I am thinking of a file-system based memory management model which would allow dynamic loading (and unloading) of components. Yes, this is a bit tricky but not impossible. I have built (and still do!) applications that utilize the same concept on a PC with great success. Each user has its own "usage pattern" for each application and that means that only a few key components are loaded in memory at any given time - which results in very good performance (=low ram consumption).
I am wondering now how many people out there would feel comfortable with looking at Firefox source code and sharing some thoughts here on the forum about memory management and individual components of Firefox.