straw poll for multi-homed operators

[number 5 in a series of unscientific surveys]

If you currently multi-home between two or more providers using IPv4:

+ why do you do it? What are the high-level goals you are hoping to achieve?
   Are you finding that you are achieving them?

+ how often does your traffic shift between transit providers due to
   a failure of some kind triggering a re-homing?

+ how often do you manually shift traffic, and why? Just inbound traffic?
   Or outbound too?

+ what impact does a manual or automatic shift in traffic between providers
   have to your users? Do their TCP sessions break? Or do you think they
   normally stay alive, maybe after a delay? What makes you think this?

+ what is *bad* about the way that multi-homing works in IPv4?

+ what is good about it?

Context is an attempt to nail down some requirements for a multi-homing
architecture in IPv6 (one that doesn't incorporate exciting up-and-to-the-
right state explosion in the DFZ).

I can summarise private replies if there is interest.