LVS or Haproxy for 50k+ concurrent connections

Howdy,

I'm curious as to the most appropriate setup for supporting at
_minimum_ 50k concurrent tcp connections scalable to 1million. We
would be using a custom protocol w/ a 1KB transfer limit per second
per connection. Each server will need to keep track of user state
while sync'ing every so often w/ the other servers. Would an LVS setup
of some form make sense here?

-b