Perhaps I am missing something from your advantage list, but why would you want to exchange routing information with a network to which you don't have a connection due to a local failure? I think you are attempting to abstract routing from the underlying physical infrastructure a bit too much. If the power is out in the carrier pop to which you are connected, they don't have a way to give you traffic so why would a multi-hop session help.
BGP being down is rarely something that happens on its own, it is typically due to something far more physical (router failure, pop outage, circuit outage, etc).
any time routing signaling comes from a source to which you can not directly deliver payload you will be in a load of grief when something goes wrong. abjure route servers. route reflectors should be in the data plane, ... in general, when layer N is not congruent with layer N-1 (and N+1), you have a recipe for exciting times. and well run ops is not supposed to be exciting. randy