I don't understand what you're doing here.
The reason we maintain packets for replay in the channel is so we can do reattach of clients to servers, this only occurs if confirmation-window-size is <> -1
Reattachment only applies to client-server connections. Why would you want to do this on the live-backup replicating connection too?
I've removed the param backup-window-size and backup channel now has window size of -1.
You would normally need to confirm each packet if you're using confirmations, but since I have set this to -1 the confirm() calls are unnecessary too.
BTW setting backup-window-size to > 0 was pointless anyway since you had set reconnectAttempts to zero, also since you weren't confirming, packets would have built up for ever and you'd have got OOM eventually.