It worked like a charm. It's a bit tedious to edit the two files to change the configuration, but once done, one process updates the database adding the new chains while the other serves the web requests. I have added both I0coin and Ixcoin this way, and it seems to go very well.
Good to hear! If you have to switch configs often, I suggest creating two versions of abe.conf. You can put the common parts in a third file and have both include it by "config FILE". I've done this with HTTP and FastCGI configurations, for example. I pass either "--config abe-http.conf" or "--config abe-fcgi.conf" to the program. abe-http.conf and abe-fcgi.conf each contain a few file-specific directives and the line "config abe.conf" to pull in abe.conf, which contains all the common stuff such as db params and datadirs.
Thanks a lot for the great software and all the help, John.
You're welcome, and thanks for testing it out.