UPDATE: 10/12/13 Google released Android 4.4.2 today and I can confirm that this now fixes the Exchange sync issue on my Nexus 5. See below for more details...
A couple of us in the office have just taken delivery of some shiny new Nexus 5's - fantastic devices we're really happy with but we've unfortunately both come across what looks to be a known issue setting up the ActiveSync connection to synchronise them with MDaemon Messaging Server.
MDaemon has an integrated ActiveSync server but this issue with the devices will also apply to those of you who use Microsoft Exchange.
