Your configuration must be doing something odd. Yes. As specifying multiple identical src_ipaddr values for several home servers resulted in 2.1.7 not to start up properly, I (mis)understood the comment
# The rest of the configuration items listed here are optional, # and do not have to appear in every home server definition. as if you could specify the values in the "localhost" home_server definition and then every other home_server section would pick up them as default. No, that's not what the wording suggests, but apperantly, it's how 2.1.7 worked -- at least in case of src_ipaddr and -X. I thought I had tried moving the src_ipaddr definitions to the individual home server sections earlier the day after I upgraded to 2.1.10, but I must have made some mistake I cannot reproduce. As you already pointed out further up in this thread, I like to debug things myself. So at least, there is a patch attached adding more debug output to proxy listener allocation and home server selection so the day I wasted on the subject may serve somebody else.