Other Editor that will handle file that's too large for memory?

(Apologies if this is the wrong category for this question, and please feel free to move it)

None of my machines have more than 32GB, but I sometimes need to edit files that are Very Much Larger (e.g. 150GB). I've tried various workarounds (sed, split the file, etc) but none are very satisfactory.

So: does anyone know of an editor that (a) runs under FreeBSD, (b) will handle files of arbitrary size (presumably by paging them in and out), and, preferably, (c) doesn't have a u/i that promotes errors?
Most likely not what you are after, but vi -F is awesome! A sample 1GB file with just "y" on each line took 15 minutes to load into vi, 4GB temporary was slowly created during that. vi -F, it's lightning fast. Vi stayed 10 megs virtual, 2 megs RSS all the time.

I don't get why sed(1) is not suitable for your, unless the FreeBSD implementation does something stupid it should never try to load the whole input file in memory but work in smaller buffered units.