For those using the new FIBRE-based Relay Network, I just added the following paragraph to the public-network page:

"Note that, because bitcoind treats the -addnode argument as an extra seednode it may use, and not as a connection which it should maintain, it is recommended that you use an external daemon to keep the connection reliable. There is a simple connect-two-bitcoinds-together client available in the Relay Network Client Source Tree (called fibrenetworkclient after you run make) which takes, as arguments, two bitcoind instances, and connects them to each other, reliably reconnecting if one goes down."