IMHO, the XEmacs approach of using a portable dumper is the better option. I prefer that one not only because it frees us from having to worry about the details

IMHO, the XEmacs approach of using a portable dumper is the better option. I prefer that one not only because it frees us from having to worry about the details of executable formats, but because the same machinery that lets us find and relocate all the intra-lisp-heap pointers would also let us write a compacting GC, which is important for long-running programs like Emacs.