I tend to use haproxy only in situations where I don't have access to a 'proper' load balancer (e.g, something which does tcp connection state failover and all

I tend to use haproxy only in situations where I don't have access to a 'proper' load balancer (e.g, something which does tcp connection state failover and all that jazz); make it listen on lo0 on each client server, who then just talk to 127.0.0.1:whatever.. It does mean you are doing health checks from each client service/app, but it only eats a few mb of ram, and then you don't have to deal with making your haproxy service HA :}