The 1998 paper contemplated speculatively a combination of small-scale gene doubling (as evidenced by the immediate neighborhood of EF-Tu/EF-G) and of a large-scale gene cluster doubling (as evidenced by the spacing between secE/secY and rpoH-A/rpoD) with the hope of a future deeper understanding based on folding structures. Now the referee makes an exciting suggestion that may, if executed successfully, go some way to satisfy that hope.
I have only a few comments, which might improve the manuscript.